MDLSITE-2009 Clarify paths

- Ensure that gitmirror exists.
- Ensure all operations happen there.
MDLSITE-2009 better process ordering.

It's desirable to always follow the "master first,
then stables from older to newer" rule when creating
the new commits. Commit dates are as package dates and
they have implications about how sourceforge displays them.
MDLSITE-2009 integration is origin in gitmirror
MDLSITE-2009 prevent shell error, orphaned command.
Merge pull request #1 from stronk7/clarify_paths

MDLSITE-2009 Clarify paths
Very nice thanks Eloy!