Bump PHP && PHPUnit versions && Fix tests

Author: ekinhbayar

.travis.yml

@@ -1,12 +1,13 @@
 language: php
 
 php:
-  - "5.5"
-  - "5.6"
+  - "7.0"
+  - "7.1"
+  - "nightly"
 
 before_script:
   - composer self-update
-  - composer install
+  - composer update
 
 script:
   - phpunit --configuration phpunit.xml.dist --coverage-text --coverage-clover=coverage.clover

composer.json

@@ -13,9 +13,9 @@
         }
     ],
     "require": {
-        "php": ">=5.5"
+        "php": "^7"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.3.*"
+        "phpunit/phpunit": "^6"
     }
 }