Adding stable 8.1 to travis.yml

.travis.yml

@@ -55,6 +55,8 @@ matrix:
       env: DB=pgsql
     - php: 5.4
       env: "DB=mysql CORE_BRANCH=stable8"
+    - php: 5.4
+      env: "DB=mysql CORE_BRANCH=stable8.1"
     - php: 5.4
       env: "DB=mysql CORE_BRANCH=stable7"