Added functionality to track bluetooth state changes

Used the Bluez dbus API to fetch and track the bluetooth state changes.
This patch makes use of bluez4 API and it changes quite a lot in bluez5.
Once the move is done to bluez5, this API usage also has to be modified.

Signed-off-by: Sateesh Kavuri <sateesh.kavuri@gmail.com>
Removed the hack to enable USB transport forcefully

Signed-off-by: Sateesh Kavuri <sateesh.kavuri@gmail.com>