Merge pull request #165 from mozilla-services/master

sync to master
Merge pull request #167 from jrconlin/dev

Added alter table sql; more debug
Add temp debugging for client add remove

look for +++ and --- in logs
Flag missing from table state.
Issue 171: Handle multiple WebUI clients.

* Adding instance list for devices.
* fixed mutex to be RW
* added debug on Quitter for worker.