cache brew

.travis.yml

@@ -25,6 +25,7 @@ cache:
     - $HOME/.m2
     - $ANDROID_HOME/licenses/
     - $HOME/Library/Caches/Homebrew
+    - /usr/local/Cellar
 before_cache:
   - rm -rf $HOME/.gradle/caches/modules-2/modules-2.lock
   - rm -rf $HOME/.gradle/caches/*/plugin-resolution/