`fs rename` command for modifying template values

When the FS template is changed (for example to make use of the new features in https://github.com/openmicroscopy/openmicroscopy/pull/2701), sysadmins may want to rearrange their old data to match the new template. The `bin/omero fs rename Fileset:ID` command now does that.

**Integration tests & testing instructions coming after a rebase**