Add builder option to allow Blueteeth to handle 'unrecoverable' errors

[sureshjoshi]

Errors that come out of the Android BLE system can be unrecoverable, until Bluetooth is reset (or the app is closed and re-opened).

As part of a builder option, 'unrecoverable' errors can either be passed along to the developer, or handled internal to Blueteeth.

[sureshjoshi]

As per issue #16 - Need to figure out what the preferred error mechanism is. Right now, have a hook for Exceptions (of some sort), but that might not be ideal. Maybe extend Result to take in 2 parameters, and create a custom error class?