Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_analytics

Conflicts:
	Android/res/xml/preferences.xml
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_analytics

Conflicts:
	Android/res/xml/preferences.xml
added ga tracking for the flight action buttons usage.
added documentation stub for the drone event types.
bug fix.
added tracking for mavlink connection methods.
fixed license issue with travis ci.
second attempt at fixing travis ci license issue.
updated connection type session on disconnection.
fix gradle tools version.
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_analytics
updated gradle tools version to support android studio beta release.
updated the android plugin declaration style.
Parameters: Updating parameter description file
Merge pull request #828 from DroidPlanner/parametersUpdate

Parameters: Updating parameter description file
completed analytics feature list.
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_analytics
specifying required libraries for the travis ci build.
attempt to fix travis ci build issues by using deprecated google analytics hit builder.
Merge pull request #829 from DroidPlanner/feature_analytics

Google Analytics update
Updated German translations, removed "hello world" strings
Merge pull request #831 from zumbrunnen/de_translation_update

Updated German translations, removed "hello world" strings
Android: Trying a dirty fix for issue #833.

Increased the buffer size and added a catch for buffer overflow
exceptions.