Really hide!

For GCI task http://google-melange.appspot.com/gci/task/view/google/gci2013/5327990548332544! (also, issue #3)

Note: The keycombo ctrl+command+shift+r is hardcoded, see inputserver.

## Implementation details:
The input server filter watches for the keycombo, and sends that to the current running app, or starts the app. The app starts recording in the background, with the icon either visible or hidden, and the window hidden. When recording stops, the window will be shown again and encoding will start as normal.