The client/server URL is needed for go-neb to work correctly, and to remove our complete dependence on federation.
The federation URL is also configurable so servers that don't wish to federate can specify a local address.
This is part of a rewrite for Dimension to better support integrations. Only the bare minimum scalar APIs are implemented at this point - dimension is non-functional.
This is a breaking change because of the structure change for upstreams. Instead of being an object, it is now a list. Existing configurations are not guaranteed to work.
Adds #108 and starts work on #22 (upstream config).
