Fixes problem in the (currently disabled) alpha feature of live tracking

Fixes https://github.com/diydrones/droneapi-java/issues/1
But not an urgent pull because this feature is currently disabled in the
droidplanner GUI.
Merge pull request #1174 from geeksville/dapiLiveFix

Fixes problem in the (currently disabled) alpha feature of live tracking
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into drone_locator