Add hardware keys support from CM

also rename and clean Navbar.java, change some icons
better lockscreen settings icons
Bluetooth: DUN: Add DUN profile support in Settings APP

It registers service listener for DUN profile with the
BT adapter, and it will track the profile status with
the service listener state chnages.

It also has support for DUN profile connection status
updation and DUN Disconnection from server.

Change-Id: I83d4919821cb095429ff7e73a8974d92c4df086c