Managed repository template path expansions

Refactors managed repository template path expansion to allow extra terms. Testing should be inspired by https://github.com/openmicroscopy/ome-documentation/pull/836 at http://www.openmicroscopy.org/site/support/omero5-staging/sysadmins/fs-upload-configuration.html. Try setting `omero.fs.repo.path` to various values then importing.
I'd still vote for not interesting new ones.