Added identity_provider relationship to group_membership to deprecate
group_membership.origin
running the UUID column cleanup in a JdbcMigration so the application
can continue to start up in case of error. If validation fails, you'll
see a WARN level log, eg:
https://gist.github.com/xtreme-will-tran/63bad757093285ef78c0
dropping unique index users.(username,origin)
Create README.md
Update README.md
updated schema diagrams
Revert "dropping unique index users.(username,origin)"
There are too many cascading side effects to this, we will address
this when we're ready to tackle users.identity_provider

This reverts commit 28d3ab06298f6b15f8e4dd0ba7c0766f41cffb3a.