Modified phpunit version for PHP 5.5 support

.travis.yml

@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 5.4
   - 5.5
   - 5.6
   - 7.0

composer.json

@@ -11,14 +11,14 @@
     }
   ],
   "require": {
-    "php": ">=5.4.0",
+    "php": ">=5.5.0",
     "laravel/framework": "~5.0",
     "phpdocumentor/reflection-docblock": "~2.0",
     "mpociot/documentarian": "^0.2.0",
     "fzaninotto/faker": "^1.6"
   },
   "require-dev": {
-    "phpunit/phpunit": "~5.0",
+    "phpunit/phpunit": "~4.0",
     "orchestra/testbench": "~3.0"
   },
   "autoload": {