Android: Make getDeployDeviceSerialNumber not start a avd automatically

This allows the caller to do that as a fallback.

Change-Id: Ifd50036317c7df4fe77fc34ea0f616c07611a517
Reviewed-by: Nikita Baryshnikov <nib952051@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
Android: Remove apiLevel parameter from connectedDevices

Both callers do filtering on the api level afterwards, so it pratically
serves no purpose.

Change-Id: I8f54f9050a66185a3799ea5b5446dec935d2d5ac
Reviewed-by: Nikita Baryshnikov <nib952051@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>