Merge pull request #8 from guillaume-mixi/master
Refactor few things

- Fix proguard config
- Remove NoProGuard interface
- Rename annotation WebViewBridge to WebViewBridgeResource
Don't let proguard shrink module constructors

Since the injector construct module by reflection, Proguard may
remove these if they're not called explicitely anywhere else, which
would result in uninstantiable modules.
Make sure module constructors don't get shrunk by Proguard.