Upgrade RNA submodule to latest master

1c91e65 Fix Bug 937788 - Add releases to non-legacy API
7dbd0d6 Add basic docs and requirements
2b9dd50 Sync up setup.py's requirements with the pip requirements
5b1212f Add Release migration
7081e16 Include management commands when installed
6b40edb Doh, we need the management package too
0350421 Simplify data model and add method for retrieving notes for
        a release