This is so the different needs of each can be accounted for. For example, widgets are fairly unrestricted, so nothing really needs to prevent them. Bots on the other hand require an upstream token otherwise we can't get the bot IDs from Modular.
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.
Includes the ability to 'test' the appservice. This doesn't bother checking if the URL is set up correctly because we don't actually care about the transactions.
