Fix compiler warnings.
First commit of functional noise sensor
Clean the code of the  CSNoiseSensor.m file
Support ios6.0 and later instead of 7.0 and later.

At runtime determine whether running on ios7.0 and invoke the ios7 methods.
Refactor.
Merge branch 'unstable' into feature-audio_recording

Conflicts:
	sense platform/sensors/CSNoiseSensor.m
Merge branch 'unstable' of https://github.com/senseobservationsystems/sense-ios-library into unstable