Add a new 'get' method to model objects.

This method returns the exact response (up to serialisation) for
GET requests on a model object.

The server app now uses this method for non-HTML GET queries.
Rewrite much of the Creator, and more.
Another massive tangly dump.

This moves BRA over to the fat models way of doing things (models
respond to their own PUT/DELETE/GET requests, hooks to make the
model talk to BAPS appear), amongst some other things.
Fix typo in hash utilities.
Rejiggle formatting for player variables etc.
Items can be GOT by anyone.
Add CORS b***ocks.

Did I mention I don't like CORS?

This requires corresponding changes to the config.yml.
Simplify HTML view.

Object names are now just their URLs, and a lot of the unnecessary lard
in player variables etc. has been trimmed out.
Add shortcuts for calling methods on children.

get_resource, put_resource and delete_resource methods are here for all your
getting, putting or deleting a child of a model object by its URL needs.

find_resource now takes a block, making it easier to do stuff with it.
Probably broken changes to the controller.

Trying to make the controller eventually just do GET/PUT/DELETEs
on the model, to make things nice and orthogonal.  Or something like that.  I
don't know...