Add ability to disconnect and remove simulated device

[tomrozb]

I'm trying to write a driver test with simulated device, that checks connection state presented in app UI when the BLE connection is lost. I've not found API in blemulator to disconnect and remove the simulated device.

Despite the fact I found a workaround for this I'd like to see official API for removing simulated devices.

Right now I just call onDisconnect on the simulated device and return false from onConnectRequest. I think removing the device from blemulator would be much better solution.