Bug 1020847 - Add handwriting IME for Simplified Chinese

`handwritingPadsManager` should `start()` even without the handwriting engine. We want to `start()` the world regardless of the current status of the keyboard app. If `start()` is too heavy to run during app start you should offload it (instead of changing where `start()` is called).

Thank you to give it a thought on offloading app start-up though.