Stopped encoding the file contents in the uri mapper (and its tests); the reply builder should do that instead.
Added the tested uri mapper to the http server, and finagled the old echo server into the enclosing http server function and receive message function.
Implemented tests for the receive_connection function.
Added parse_request function to the http server and tweaked tests for the receive_connection function.
Added build_response function to http_server.py.