Added fields to range finder clarifying sensor properties
Added rangefinder message to MAVLink app
Untangled local pos and distance messages, now sending distance messages only for actual distance measuring devices
Merged master into mavlink_range_finder
Merged master
Merge pull request #827 from PX4/mavlink_range_finder

Mavlink range finder
fw_config_fixes
Merge branch 'master' of github.com:PX4/Firmware into ekf_params