Store runtimes in the /runtimes subdirectory

The new default path for runtimes is now /opt/software/runtimes
Use the right OverlayFS options for Linux 3.18

This should close bug #1
Also improve the runapp code slightly.
trivial: Split out binreloc, we don't need it anymore
Update mime definition
Add manpages
Make sure xmlto is found
Implement very basic dependency check on software removal

We later want to have the manager emit a list of broken packages, and
also allow removing a package including its dependencies.
But for now, this very simple implementation will do the job.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	tools/runapp/runapp.c