Add camera button intent receiver.

Camera button broadcast receiver registration was missing in manifest
file of Camera application. So camera hardware button long click was
not launching camera application. This change registers the broadcast
receiver in Android manifest file.

Change-Id: I53e6f7029fbe24c303b500487a54edb10e2b8ac9
CRs-Fixed: 574354
Merge pull request #1 from omnirom/android-4.4

Add camera button intent receiver.