first version of monitored navigation

adapted from the SMACH stuff from the waypoint_patroller. This works as an action server that receives exactly the same goals as move_base. Thus, to use this, one just needs to use server 'monitored_navigation' instead of 'move_base', and, instead of launching scitos_2d_nav.launch, launch

```
roslaunch monitored_navigation monitored_nav.launch map:=bla
```