Bug 1038645: Asynchronous starting and stopping of profile managers (under bluetooth2/), r=btian

Profile managers use the new class |BluetoothProfileResultHandler|
to signal the result of initializing of cleaning up operations to
|BluetoothServiceBluedroid|. |BluetoothServiceBluedroid| proceeds
once all profile handlers have finished.

Future patches will build upon this patch to create completely
asynchronous profile managers.
Bug 1038645: Add result-handler class for Bluetooth Handsfree profile (under bluetooth2/), r=btian
Bug 1038645: Asynchronous Bluetooth Handsfree init and cleanup methods (under bluetooth2/), r=btian
Bug 1038645: Asynchronous Bluetooth Handsfree connection handling (under bluetooth2/), r=btian
Bug 1038645: Asynchronous Bluetooth Handsfree voice-recognition functions (under bluetooth2/), r=btian
Bug 1038645: Asynchronous |BluetoothHandsfreeInterface::VolumeControl| (under bluetooth2/), r=btian
Bug 1038645: Asynchronous |BluetoothHandsfreeInterface::DeviceStatusNotification| (under bluetooth2/), r=btian
Bug 1038645: Asynchronous Bluetooth Handsfree response methods (under bluetooth2/), r=btian
Bug 1038645: Asynchronous |BluetoothHandsfreeInterface::PhoneStateChange| (under bluetooth2/), r=btian