Merge pull request #10 from senseobservationsystems/motion_prefs

Motion prefs
Removed android support library (should be inherited from
sense-android-library project)
Updated proguard configuration
Added stuff/build/ folder to hold files for exporting an apk,
updated proguard-project.txt, renamed stuff/market/ to stuff/playstore/.
Merge branch 'release-2.7.0' into develop