Use RC build on travis

Author: cedricziel

.travis.yml

@@ -17,9 +17,9 @@ cache:
 matrix:
   include:
   - env: IDEA_VERSION="IU-2017.2.5" PHP_PLUGIN_VERSION="172.4155.41"
-  - env: IDEA_VERSION="IU-2017.3" PHP_PLUGIN_VERSION="173.3942.13"
+  - env: IDEA_VERSION="IU-173.3942.15" PHP_PLUGIN_VERSION="173.3942.13"
   allow_failures:
-  - env: IDEA_VERSION="IU-2017.3" PHP_PLUGIN_VERSION="173.3942.13"
+  - env: IDEA_VERSION="IU-173.3942.15" PHP_PLUGIN_VERSION="173.3942.13"
 
 before_install:
 - "export ORG_GRADLE_PROJECT_ideaVersion=${IDEA_VERSION}"