Anton/sync groups and verticals

This fixes https://openedx.atlassian.net/browse/BLD-1095

NB: before merge `ENABLE_GROUP_CONFIGURATIONS` should be set to default value.

Please review: @tymofij  @cahrens 

@explorerleslie Sandbox is http://studio.auraz.m.sandbox.edx.org/
Cale convinced me with that last statement-- we can't be creating drafts just by visiting the unit page in Studio. Alex, I think the display names can't be saved in the verticals. That's unfortunate for unused groups, but unavoidable. I know I was very against display names being out of sync, but given the draft concern, it might be best to store the display name at the time the group was created, and then never persist an update. The other option is to simply show the default vertical name in the case of unused groups.