Added try catch for extended events

* Version 1.0.11:
* Date: 14th Mar 2013
* Compatible with Spokes SDK version(s): 2.8.24304.0, 2.7.14092.0
* Changed by: Lewis Collins
*   Changes:
*     - Added try/catch exception handling and debug around registering
for extended headsetstatechange
*       and extended basestatechange events that were used for
"asyncronous" method of receiving serial
*       numbers from device (works for base serial, NOT for headset
serial)
*     - Also added "syncronous" method of obtaining serial numbers
following discussion with Ramesh Mar 2013
*       however this is NOT working for base OR headset serial! (So left
in "asyncronous" method for now,
*       at least we have base!)