- cleaned up the DeviceService.connect() variants
- discovery: pass the device candidate around instead of the mac address
Attempts to fix#512, #514, #518
HOWTO:
1) Pair you normal Pebble (not necessary if already done), make sure it was connected once
2) Unpair your LE pebble if already paired
3) Switch on "Always prefer BLE" in Pebble Settings
4) Tap on the + in Control Center to add a new device
5) Pair your Pebble-LE XXXX or Pebble Time LE XXXX inside Gadgetbridge's Device Discovery actibity
Now Gadgetbridge will connect to your LE Pebble when tapping on Pebble XXXX if "Always Prefer BLE" option is enabled.
You can easily switch back to classic LE by turning that option off again
