Architecture diagram for user messaging.
Move frontend architecture drawing into dev folder.
Merge branch 'develop' into feature/issue-949-messaging-architecture-drawing
Merge branch 'develop' into feature/issue-949-messaging-architecture-drawing
Bump librabbitmq version since it claims to fix Linux install issues that appear to be affecting doc builds on readthedocs.
Update doc build requirements to match those in requirements.pip more closely (i.e. add externals for vxpolls and wikipedia and remove protobuf).
Merge branch 'develop' into feature/issue-949-messaging-architecture-drawing
Merge branch 'develop' into feature/issue-949-messaging-architecture-drawing

Conflicts:
	requirements-docs.pip
	setup.py
Merge branch 'develop' into feature/issue-949-messaging-architecture-drawing
Add some missing arrows.
Merge branch 'feature/issue-949-messaging-architecture-drawing' into develop