trial fix for build failure

Author: huangqun

circle.yml

@@ -12,8 +12,8 @@ dependencies:
     - curl -s https://raw.githubusercontent.com/chronogolf/circleci-google-chrome/master/use_chrome_stable_version.sh | bash
 
   override:
+    - rm -rf bower_components
     - npm install
-    - bower --force update
 
   post:
     - ./node_modules/gulp/bin/gulp.js clean