* Add QueryDeviceMessages to serve up device keys and stream IDs
* Consume key change events in fedsender
Don't yet send them to destinations as we haven't worked them out yet
* Send device list updates to all required servers
* Glue it all together
* Recheck device lists when join/leave events come in
* Add PerformDeviceDeletion
* Notify clients when devices are deleted
* Unbreak things
* Remove debug logging
* Add storage layer for postgres/sqlite
* Return OTK counts when inserting new keys
* Hook up the key DB and make a test pass
* Convert postgres queries to be sqlite queries
* Blacklist test due to requiring rejected events
* Unbreak tests
* Update blacklist
