Enqueueing request in onDeviceDisconnected causes problems

[philips77]

When a connection is disconnected by remote side (status 8), and the manager calls notifyDeviceDisconnected(), it first calls close(), then onDeviceDisconnected().
If a new connection request was added in onDeviceDisconnected() is will be proceeded immediately, as the mOperationInProgress` flag was cleared.
The new request fail callback would be invoked a moment later with the old's request status (8).

[philips77]

Found in 2.0-beta7

[philips77]

Fix released in 2.0-beta9.

[philips77]

This might have broken #25 again. More testing needed.