Android Bluetooth partial support. Socket client and Device discovery.

Socket in client mode and device discovery is implemented.
Server socket is feasible and can be added later.
Some of the Qt Bluetooth API's cannot be ported because
Android Bluetooth API is a subset.
Other parts (Service discovery, L2CAP, Channel number, etc) are not
available on Android.

Kudos goes to Lauri Laanmets <lauri.laanmets@proekspert.ee>