Merge pull request #9 from owncloud/fix-travis-branch-stable8

Fix the travis target branch and the branches.only setting

.travis.yml

@@ -7,14 +7,15 @@ php:
 
 env:
   global:
-    - CORE_BRANCH=master
+    - CORE_BRANCH=stable8
     - APP_NAME=files_locking
   matrix:
     - DB=sqlite
 
 branches:
   only:
     - master
+    - /^stable\d*$/
 
 before_install:
   - wget https://raw.githubusercontent.com/owncloud/administration/master/travis-ci/before_install.sh