Adding battery level and better legend docking detection

* Version 1.0.17:
* Date: 24th May 2013
* Compatible/tested with Spokes SDK version(s): 2.8.24304.0
* Changed by: Lewis Collins
*   Changes:
*     - Adding BatteryLevelChange event notification when the battery
charge state
*       changes.
*     - Adding GetBatteryLevel methods to be called by app in response
*       to the above event notification event to obtain the current
battery
*       level.
*     - Minor fix to docking detection of Legend UC