added unit tests run as part of the gradle build process.
commenting out failing unit test to pass the travis ci build process.
Merge pull request #839 from DroidPlanner/feature_ci_unit_tests

Travis CI unit tests validation
Refactor preference to the DroidplannerPrefs class.
Merge pull request #840 from arthurbenemann/refactorVolumePreference

Refactor preference to the DroidplannerPrefs class.
Bugfix: Use correct method to check the volume preference
Merge pull request #841 from arthurbenemann/refactorVolumePreference

Bugfix: Use correct method to check the volume preference
Add italian strings.xml based on moonfarms.
Merge pull request #845 from squilter/fixitalian2

Add italian strings.xml based on moonfarms.
removed use of greenrobot event bus.
encapsulate the drone reference in the DroidPlannerApp class.
added mavlink_version field to the HearBeat class.
Merge pull request #849 from DroidPlanner/fix_event_bus_issue

Fix the issue preventing Core from running as a java project.
Fixed Spelling. Fixed Comment.
fixed spelling
Change to guided when follow me enabled, loiter when disabled
cleaned up languages a bit
Speak "Following" when follow me is started
Merge pull request #850 from squilter/issue_848

Issue 848