Patch queue functionality

[bonzini]

• [x] Basic support in database and web interface
• [x] Add "queue:XXX" to search query
• [x] Allow downloading queue as mbox
  • [x] Add /my-queues/PROJECTNAME, which automatically restricts the my-queues query to a project
  • [x] Add /my-queues/PROJECTNAME/NAME to format queues like search results
  • [x] Add /my-queues/PROJECTNAME/NAME/mbox view, similar to series mbox view
• [x] Allow emptying a queue from the my-queues page
• [ ] Per-project WatchedQuery
• [x] Sanitize queue names
• [ ] REST API improvements
  • [ ] Expose queues in REST API as /projects/.../queues/...
  • [ ] PATCH/POST/PUT on series can add/remove series from a queue
  • [ ] Add mbox_uri in project queue view
  • [ ] Expose watched queries in /users
  • [x] Add mbox_uri to SeriesSerializer, redirecting to mbox view from www/views.py

[elmarco]

@bonzini there is a wip branch for this? thanks