STK should indicate that it is busy when connecting wiimotes

[altcoin]

Currently, the STK gui simply freezes once a user clicks OK on the Add Wiimote dialog for anywhere from 5 to 15 seconds (~5 sec to scan + 2-3 sec per wiimote).
The gui should indicate to the user that something is happening, eg by displaing a spinner, or printing "Scanning..." and then "Connecting..." to the gui.