Update timestamp of the RPA migration so it runs

The RPA migration was run in a previous (buggy) form in production, and
needs to have its timestamp updated so that the corrected migration will
run.
Merge pull request #177 from alphagov/redo_rpa_migration

Update timestamp of the RPA migration so it runs
Rename second RPA migration to avoid name conflict
Merge pull request #178 from alphagov/fix_duplicate_migration_names

Rename second RPA migration to avoid name conflict