* 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
* Fix New users appear in /keys/changes
* Create blank device keys when logging in on a new device
* Add PerformDeviceUpdate and fix a few bugs
- Correct device deletion query on sqlite
- Return no keys on /keys/query rather than an empty key
* Unbreak sqlite properly
* Use a real DB for currentstateserver integration tests
* Race fix
* Recheck device lists when join/leave events come in
* Add PerformDeviceDeletion
* Notify clients when devices are deleted
* Unbreak things
* Remove debug logging