build: fixed .travis.yml

.travis.yml

@@ -13,10 +13,9 @@ notifications:
         on_success: change
         on_failure: change
     webhooks:
-        urls:
-	    - https://webhooks.gitter.im/e/66485d8f591942052faa
-	on_success: always
-	on_failure: always
+        urls: https://webhooks.gitter.im/e/66485d8f591942052faa
+        on_success: always
+        on_failure: always
 matrix:
     fast_finish: true
     allow_failures: