Use local phpunit

Author: pmatseykanets

.travis.yml

@@ -15,4 +15,4 @@ 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