[TASK] Activate travis for 6.1 branch

Change-Id: I21f5a57ac8b0f90c7c16af39ad882feb3243e720
Releases: 6.2, 6.1
Reviewed-on: https://review.typo3.org/20227
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn

.travis.yml

@@ -9,6 +9,7 @@ env:
 branches:
   only:
     - TYPO3_6-0
+    - TYPO3_6-1
     - master
 
 services: