History of changes to facility resources

[jmwohl]

For the Revisit API, we wanted to make available a history of changes to a specific facility resource so that we could track changes over time and easily rollback errant changes.

https://github.com/SEL-Columbia/Revisit-Server/wiki/API-Documentation-v0.2.2#history-and-rollback-queries

Example response:
http://revisit.global/api/v0/facilities/5480d81d2ecfcf6908432694.json?history