Amend travis config

Author: DannyvdSluijs

.travis.yml

@@ -28,6 +28,11 @@ matrix:
     - php: nightly
   fast_finish: true
 
+branches:
+  only:
+    - master
+    - develop
+
 install:
   - curl -s http://getcomposer.org/installer | php
   - php composer.phar install --dev --no-interaction $COMPOSER_FLAGS