diff --git a/.gitignore b/.gitignore
index 67058cfc..88c88d30 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,6 @@ test/dummy/.sass-cache
 !/test/sandbox/.gitkeep
 
 .ruby-version
+
+Gemfile.lock
+gemfiles/*.lock
diff --git a/.travis.yml b/.travis.yml
index f942f569..cc0f1e84 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,14 @@
 language: ruby
 sudo: false
 cache: bundler
+before_script: bundle install --jobs=3 --retry=3
 
 rvm:
-- 2.2.7
-- 2.3.4
-- 2.4.1
+  - 2.2.7
+  - 2.3.4
+  - 2.4.1
+
+gemfile:
+  - gemfiles/Gemfile.rails-4-2stable
+  - gemfiles/Gemfile.rails-5-0stable
+  - gemfiles/Gemfile.rails-5-1stable
diff --git a/Gemfile.lock b/Gemfile.lock
deleted file mode 100644
index 623a700a..00000000
--- a/Gemfile.lock
+++ /dev/null
@@ -1,144 +0,0 @@
-PATH
-  remote: .
-  specs:
-    pdfjs_viewer-rails (0.0.9)
-      rails (> 4.2.0)
-      sass-rails (~> 5.0)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    actionmailer (4.2.7)
-      actionpack (= 4.2.7)
-      actionview (= 4.2.7)
-      activejob (= 4.2.7)
-      mail (~> 2.5, >= 2.5.4)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-    actionpack (4.2.7)
-      actionview (= 4.2.7)
-      activesupport (= 4.2.7)
-      rack (~> 1.6)
-      rack-test (~> 0.6.2)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (4.2.7)
-      activesupport (= 4.2.7)
-      builder (~> 3.1)
-      erubis (~> 2.7.0)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    activejob (4.2.7)
-      activesupport (= 4.2.7)
-      globalid (>= 0.3.0)
-    activemodel (4.2.7)
-      activesupport (= 4.2.7)
-      builder (~> 3.1)
-    activerecord (4.2.7)
-      activemodel (= 4.2.7)
-      activesupport (= 4.2.7)
-      arel (~> 6.0)
-    activesupport (4.2.7)
-      i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
-      minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
-      tzinfo (~> 1.1)
-    addressable (2.4.0)
-    arel (6.0.3)
-    builder (3.2.2)
-    capybara (2.7.1)
-      addressable
-      mime-types (>= 1.16)
-      nokogiri (>= 1.3.3)
-      rack (>= 1.0.0)
-      rack-test (>= 0.5.4)
-      xpath (~> 2.0)
-    cliver (0.3.2)
-    concurrent-ruby (1.0.2)
-    erubis (2.7.0)
-    globalid (0.3.6)
-      activesupport (>= 4.1.0)
-    i18n (0.7.0)
-    json (1.8.3)
-    loofah (2.0.3)
-      nokogiri (>= 1.5.9)
-    mail (2.6.4)
-      mime-types (>= 1.16, < 4)
-    mime-types (3.1)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0521)
-    mini_portile2 (2.0.0)
-    minitest (5.9.0)
-    multi_json (1.12.1)
-    nokogiri (1.6.7.2)
-      mini_portile2 (~> 2.0.0.rc2)
-    poltergeist (1.9.0)
-      capybara (~> 2.1)
-      cliver (~> 0.3.1)
-      multi_json (~> 1.0)
-      websocket-driver (>= 0.2.0)
-    rack (1.6.4)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails (4.2.7)
-      actionmailer (= 4.2.7)
-      actionpack (= 4.2.7)
-      actionview (= 4.2.7)
-      activejob (= 4.2.7)
-      activemodel (= 4.2.7)
-      activerecord (= 4.2.7)
-      activesupport (= 4.2.7)
-      bundler (>= 1.3.0, < 2.0)
-      railties (= 4.2.7)
-      sprockets-rails
-    rails-deprecated_sanitizer (1.0.3)
-      activesupport (>= 4.2.0.alpha)
-    rails-dom-testing (1.0.7)
-      activesupport (>= 4.2.0.beta, < 5.0)
-      nokogiri (~> 1.6.0)
-      rails-deprecated_sanitizer (>= 1.0.1)
-    rails-html-sanitizer (1.0.3)
-      loofah (~> 2.0)
-    railties (4.2.7)
-      actionpack (= 4.2.7)
-      activesupport (= 4.2.7)
-      rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (11.2.2)
-    sass (3.4.22)
-    sass-rails (5.0.4)
-      railties (>= 4.0.0, < 5.0)
-      sass (~> 3.1)
-      sprockets (>= 2.8, < 4.0)
-      sprockets-rails (>= 2.0, < 4.0)
-      tilt (>= 1.1, < 3)
-    sprockets (3.6.3)
-      concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
-    sprockets-rails (3.1.1)
-      actionpack (>= 4.0)
-      activesupport (>= 4.0)
-      sprockets (>= 3.0.0)
-    sqlite3 (1.3.11)
-    thor (0.19.1)
-    thread_safe (0.3.5)
-    tilt (2.0.5)
-    tzinfo (1.2.2)
-      thread_safe (~> 0.1)
-    websocket-driver (0.6.4)
-      websocket-extensions (>= 0.1.0)
-    websocket-extensions (0.1.2)
-    xpath (2.0.0)
-      nokogiri (~> 1.3)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  capybara (>= 2.1)
-  pdfjs_viewer-rails!
-  poltergeist (~> 1.5)
-  sqlite3
-
-BUNDLED WITH
-   1.12.5
diff --git a/gemfiles/Gemfile.rails-4.2-stable b/gemfiles/Gemfile.rails-4.2-stable
new file mode 100644
index 00000000..8954cfb8
--- /dev/null
+++ b/gemfiles/Gemfile.rails-4.2-stable
@@ -0,0 +1,11 @@
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "rails", github: "rails/rails", branch: "4-2-stable"
+
+group :test do
+  gem 'capybara', '>= 2.1'
+  gem 'poltergeist', '~> 1.5'
+  gem 'sqlite'
+end
diff --git a/gemfiles/Gemfile.rails-5-0-stable b/gemfiles/Gemfile.rails-5-0-stable
new file mode 100644
index 00000000..bc6f1055
--- /dev/null
+++ b/gemfiles/Gemfile.rails-5-0-stable
@@ -0,0 +1,11 @@
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "rails", github: "rails/rails", branch: "5-0-stable"
+
+group :test do
+  gem 'capybara', '>= 2.1'
+  gem 'poltergeist', '~> 1.5'
+  gem 'sqlite'
+end
diff --git a/gemfiles/Gemfile.rails-5-1-stable b/gemfiles/Gemfile.rails-5-1-stable
new file mode 100644
index 00000000..d36a06fc
--- /dev/null
+++ b/gemfiles/Gemfile.rails-5-1-stable
@@ -0,0 +1,11 @@
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "rails", github: "rails/rails", branch: "5-1-stable"
+
+group :test do
+  gem 'capybara', '>= 2.1'
+  gem 'poltergeist', '~> 1.5'
+  gem 'sqlite'
+end
diff --git a/pdfjs_viewer-rails.gemspec b/pdfjs_viewer-rails.gemspec
index 93977ff7..8f032f09 100644
--- a/pdfjs_viewer-rails.gemspec
+++ b/pdfjs_viewer-rails.gemspec
@@ -19,6 +19,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency "rails", "> 4.2.0"
   s.add_dependency "sass-rails", "~> 5.0"
+  s.add_dependency "json", "> 1.8.4"
 
   s.add_development_dependency "sqlite3"
 end