Add new assembl_version route
The call to the route ressembles:
https://sandbox-assembl.cloud.bluenove.com/data/Discussion/67/assembl_version
Note this is because we must identify that you are an admin for a debate before you can request the version. It's a shame we can't use:
https://sandbox-assembl.cloud.bluenove.com/assembl_version
But this would constitute a security failure