Add REST API

[bonzini]

This would make it possible to integrate Patchew with external applications, such as IFTTT's "Maker channel" or Jenkins.

Todo list:

• basic read-only API
• "Results" infrastructure
  • separate endpoint for results (/project/[id]/series/[msgid]/results) instead of including them in the details view
  • project results (/project/{id}/results)
  • Refactor 'results' into a database table to allow posting arbitrary results via the REST API (see issue Introduce Result model #73)
• basic write support for series/messages (flags, reviewers, ...)
• add missing features of the old API
  • importing from mailing lists (issue Convert import to REST style POST #75)
  • tracking git repositories
  • access test capabilities
  • applier-get, tester-get
  • applier-report, tester-report (PUT of results, issue Implement PUT for results #82)
  • access module config (subset of properties access in the old API, issue Submit project configuration as YAML #112)
• Token authentication

[bonzini]

Search on results is there, but applier-get and tester-get atomically change the result to pending too and do more updates. Ideas welcome on whether this should become a separate action, or whether PATCH could be used too...

[bonzini]

Applier-get and tester-get should be respectively GET on /series/unapplied/ and POST on /projects/ID/get-test.

[bonzini]

Posted support for token authentication.

[bonzini]

And everything that's missing is now available at bonzini/patchew#rest-client.

[bonzini]

Merged.