Create a Tor PT server for Conjure

There's a few details we need to sort out for what the Conjure bridge is going to actually look like. The refraction networking relay station code is responsible for negotiating IP endpoints with the Conjure client and speaking the server side of whichever obfuscation protocol the client chose (in our case this will likely be obfs4).

Once the relay station strips off this obfuscation layer, it should send the resulting traffic to our Conjure bridge. We might have to work with Eric and the refracton networking relay station maintainers to sort out the details, but this will ideally speak something like Tor's ExtOrPort PT spec sent over an encrypted connection with with the bridge and be able to carry information like the client's address so we can do metrics.