Enable Bluetooth LE feature (android.hardware.bluetooth_le)

Tested only on endeavoru. Official sources claim that enrc2b should also be
supported.

"That’s why we’ve released a number BLE compatible devices, like the
HTC One, HTC One X+, HTC Butterfly and Droid DNA, with an open API for
developers interested in leveraging BLE in their apps."

                        -- http://blog.htc.com/2013/03/htcdev-ble-api/

Change-Id: Id8aac452f3143d77e990b82b35cf8bbfc74314e4