Added broadcast when the sense service has started

Added broadcast notification for when the Sense service is started.
Applications can implement a broadcast receiver to do the necessary setup when the sense service is started (e.g. add subscribers, cortex sensors)

Removed the starting of the main application when the service is created. Can given undesired behaviour when the sense service is disabled but created onboot.
@pimnijdam could you qa and merge? Will implement the broadcast receiver for smelly feet and Goalie, ifif this is not done already.