Run vendor'd version of phpunit

Author: lukewaite

.travis.yml

@@ -15,7 +15,7 @@ before_script:
   - travis_retry composer update ${COMPOSER_FLAGS} --no-interaction --prefer-source
 
 script:
-  - phpunit --coverage-text --coverage-clover=coverage.clover
+  - vendor/bin/phpunit --coverage-text --coverage-clover=coverage.clover
 
 after_script:
   - wget https://scrutinizer-ci.com/ocular.phar