Request now has a Write receiver method that will write to the passed io.Writer. Client now has Do method that will send the request and return the respons and any errors. Also Renamed the Client
field to Session, which was mistakenly changed.
Completed test to check that each method we support works and can produce valid requests. The requests are compared to requests that have been proven valid. This test also checks that the RTSP
client communicates over tcp correctly. i.e. we have set up a client and server, and we check that this communication happens correctly.