Update script to gradlew clean test in TravisCI

Author: Mert-Z

.travis.yml

@@ -3,7 +3,13 @@ language: java
 services:
  - cassandra
 
+before_install:
+ - chmod +x gradlew
+
 before_script:
  # give some more time for Cassandra to finish startup and actually test it
  - sleep 10
  - sudo service cassandra status
+
+script:
+ - ./gradlew clean test --debug --tests mertz.security.oauth2.provider.token.store.cassandra.CassandraTokenStoreTests