use system installed phpunit

Author: robocoder

.travis.yml

@@ -6,8 +6,4 @@ php:
   - 5.5
 #  - hhvm
 
-before_script:
-    - wget http://getcomposer.org/composer.phar
-    - php composer.phar install --dev
-
-script: ./vendor/bin/phpunit tests
+script: phpunit tests