Merge pull request #62 from senseobservationsystems/temp_fix_proximity

Improved reiiability and energy use of proximity sensor
Merge pull request #60 from senseobservationsystems/fix_sense_api_docs

Fix sense api docs
Merge branch 'fix_magnetic_field' into release-2.7.0
Update android support library to rev 13
Deleted proguard config files (not used for library projects)
Added SenseApplication helper class to library, removed it from demo
project
Updated GCM library
Fixed name of rotation rate sensor in burst mode
Merge branch 'release-2.7.0' into unstable