android-daemon: Disable backup capabilities

Since the private key is stored unencrypted in the private store of the application, it
is better to omit the backup capability in favor of security.
Merge pull request #76 from morgenroth/Disable-android-daemon-backup

android-daemon: Disable backup capabilities
android-daemon: Add Bluetooth-LE scanning
android-daemon: Remove redundant throttle of discoveries in BleManager