Using scitos 0.22.7 and prepare for release

I started working on a release version with a new mira that I debianised as a package called `mira-scitos` which is now available on our Debain server. It's build from here: https://github.com/strands-project/mira_strands. Kudos to @creuther for a little help on this. So, this branch of `scitos_drivers` now depends on `mira-scitos` as a `build_depend`. I have added this to our own rosdep, which however is only being used if people copy https://raw.githubusercontent.com/strands-project/rosdistro/strands-devel/rosdep/sources.list.d/50-strands.list into their `/etc/ros/rosdep/sources.list.d` and run `rosdep update`. I don't thing we can get the mira-scitos key into the official rosdep distribution, as it's not an official package anywhere (yet). But that shouldn't be a big problem. The build farm will resolve this correctly and then the debian package will install it from our repo. 

as this Debian package install MIRA into /opt/mira-scitos I changed the search strategy in here to search this path in addition to the `MIRA_PATH` env variable. So, it now builds without specifically setting those at build time.

Let me know if you consider this all useful or not or if I missed any problems.