feat(workflow): add initial state/action registration

introduce `superdesk.workflow` module with `workflow_state` and
`workflow_action` registers

SD-1213 SD-1209
test(workflow): improve get action by state test case
Merge pull request #421 from petrjasek/feat-workflow

feat(workflow): add initial state/action registration
[SD-1214] Instances of actions for states
[SD-1214] Instances of actions for states
[SD-1220] Create missing privileges
[SD-1217] Backend: All ingested items will have the state ingested
[SD-1220] Create missing privileges - improvements
Merge remote-tracking branch 'upstream/feat-workflow' into feat-workflow
[SD-1220] Wired up missing privileges
Merge remote-tracking branch 'upstream/feat-workflow' into feat-workflow
[SD-1216] Backend: Implement that actions update the state. Implemented 'fetched' state
Merge remote-tracking branch 'upstream/feat-workflow' into feat-workflow
[SD-1225] Refactor spike to use state
Fixing as per PR comments.
[SD-1225] use config value for state
fixing the behave test.
[SD-1225] use base schema in spike endpoint
[SD-1209] state change triggers a new version

(cherry picked from commit abc9521b47f39baceea6a8be915d2a534660b35b)

Conflicts:
	apps/archive/archive_spike.py
[SD - 1215] Creating a new version after incrementing the version number