Update BatterService and HealthThermometerService to use
up-to-date BLE APIs.
Note: HealthThermometerService::updateTemperature() will
not check GAP connection which should be taken care of by
the caller.
In the process, the path has been shortened and the unecessary ble
directory between FEATURE_BLE and the actual implementation has been
removed.
commit id of ARMmbed : 17728a824c7273e16b6b74fae871e2997c88ecd1