Doesn't crash when can't access usb device.
Merge pull request #954 from squilter/issue_803

#803: Doesn't crash when can't access usb device.
Remove TAKEOFF from mission item fragment type list if there is more than 1 item in mission list
Allow LAND and RTL mission items to be set only in the end of mission list
Fix TAKEOFF item handling
Stop new mission items addition after RTL or LAND
Merge pull request #959 from alextel69/fix-takeoff-land-sequence

Fix TAKEOFF-LAND (RTL)  sequence

Closes #794
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_android_wear

Conflicts:
	Android/src/org/droidplanner/android/fragments/helpers/BTDeviceListFragment.java
specified google play services version in gradle file.
Merge branch 'feature_android_wear' of https://github.com/ne0fhyk/droidplanner into feature_glass

Conflicts:
	AndroidLib/build.gradle