Enable redis ext on travis

.travis.yml

@@ -12,6 +12,7 @@ matrix:
     fast_finish: true
 
 before_script:
+  - echo "extension = redis.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - echo "extension = mongodb.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - echo "extension = amqp.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - if [ "$deps" == "low" ]; then composer update --prefer-source --prefer-lowest --prefer-stable; fi