* Initial refactoring of the LegacyMotionSensor out into a top level class
* Added filtering to remove gravity from the TYPE_ACCELERATOR sensor readings
Added tests around the LegacyMotionSensor
Merge pull request #1298 from crankycoder/features/1297-filter-gravity

Features/1297 filter gravity
Add dialog for testing motion detection.
This is accessible through long press on the developer screen title.
Updated to use word debug instead of test, added some docs to existing
code