Enable ameba linter

Author: veelenga

.ameba.yml

@@ -0,0 +1,13 @@
+# This configuration file was generated by `ameba --gen-config`
+# on 2017-12-23 21:39:50 +0200 using Ameba version 0.3.0.
+# The point is for the user to remove these configuration records
+# one by one as the reported problems are removed from the code base.
+
+# Problems found: 3
+# Run `ameba --only LargeNumbers` for details
+LargeNumbers:
+  Description: Disallows usage of large numbers without underscore
+  IntMinDigits: 5
+  Enabled: true
+  Excluded:
+  - spec/controllers/oauth_controller_spec.cr

.travis.yml

@@ -8,3 +8,8 @@ language: crystal
 services: postgresql
 before_script:
   - psql -c "create database $DATABASE_NAME;" -U postgres
+install:
+  - crystal deps
+script:
+  - crystal spec
+  - bin/ameba

shard.yml

@@ -50,3 +50,6 @@ development_dependencies:
   webmock:
     github: manastech/webmock.cr
     branch: master
+
+  ameba:
+    github: veelenga/ameba

spec/support/factories.cr

@@ -2,7 +2,7 @@ require "../../src/models/**"
 
 def user(**params)
   attributes = {
-    :uid      => (rand() * 10000).to_i.to_s,
+    :uid      => (rand() * 10_000).to_i.to_s,
     :login    => "johndoe",
     :provider => "github",
   } of Symbol | String => String | JSON::Type