new recovery states + bug fixes

* adds a new recovery for nav: small pause to avoid starting backtrack too soon and hard clearance of costmaps. this clearance should be ok as then the robot will try to go back and turn the head camera, re adding the obstacles that really exist

* adds a monitor and recovery for the magnetic strip and makes sure bumper recovery does not restart motors when magnetic strip is detected. To recover from magnetic strip, an explicit call to '/reset_barrier_stop' needs to be done. Requires https://github.com/strands-project/scitos_drivers/pull/88 and https://github.com/strands-project/scitos_common/pull/51