Android: Fix automatic notification sending when device demands it

Some BTLE devices enable notifications be default. However since
Android's BTLE API requires a call to
BluetoothGatt.setCharacteristicNotification(..) to forward them,
we have to peek at the ClientCharacteristicConfigurations during the
service detail discovery and tell Android to forward the notification
when required.

Change-Id: Ief419404694d70a1373218c1b8275ef868a49ddb
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>