Inbox POST from federated servers now working for statuses and follow requests.
Follow request client API added.
Start work on federating outgoing messages.
Other fixes and changes/tidying up.
This PR adds:
Statuses
New status creation.
View existing status
Delete a status
Fave a status
Unfave a status
See who's faved a status
Media
Upload media attachment and store/retrieve it
Upload custom emoji and store/retrieve it
Fileserver
Serve files from storage
Testing
Test models, testrig -- run a GTS test instance and play around with it.
