It doesn't really fit to test/, and also no other existing place.

* jenkins: decrease VTOL mission alt and FW mission use simple land wps
* startup: decrease min airspeed scaling factor for landing
* jenkins: FW mission include loiter_to_alt cmd

Move ros logs dir so that .ulg files are not in the same directory
(mission_test.py:: get_last_log() fails otherwise)

* land after offboard flying complete
* lengthen rostest time limit for tests (5 min ea)

* remove non-functional gazebo headless arg
* remove unused namespace args
* simplify mavros launch, use mavros's px4.launch instead
* fix single_vehicle_spawn spelling
* formatting with xmllint: remove empty lines, set intent to 4 spaces, add xml tag for editors, add comments to break up spections
* remove old and deprecated launch files

* add respawn_gazebo arg to be used with empty_world.launch
* catch rospy sleep method's exceptions
* fix copy-paste mistake in land state failure message

-created a test base class to centralize redundant methods among the different tests
-added mission waypoint list topic listener (this also helps make sure the simulation is ready)
-check number of mission waypoints in FCU against mission
-increase time for mavros topics to be ready from 30 to 60 seconds
-reduce position check loop rates
-clean up logging
-support QGC plan for mission file format, see #8619
-vehicle is an arg for mission test launch file, working toward other airframes
-Jenkins: fix vtol vehicle arg value
-get MAV_TYPE param and use FW radius for pure fixed-wing mission position check
-remove unused vehicle arg from test in multiple tests launch, clearing runtime warning