Full HTTP API, storage queue and SQL backend. KGM-325

- Complete HTTP API as described in README.md.
- Implement a worker queue which accepts objects to save to the
  database. This is used as a buffer to avoid doing O(N) SQL inserts,
  where N is the number of events received. Currently the buffer is
  configured to save up to 100 events of each type before storing them
  in the database.
- Implement SQL backend functions.