fs/p9p/new: ls and cat command now fully working Signed-off-by: Stephen J Day <stephen.day@docker.com>

fs/p9p/new: working client to server communication A rather large commit, this provides the first working version of running the wire protocol over a connection. It is fairly shaky but we can already get portions of the repl emitting and receiving 9p messages. Other additions include the separate of client and transport. We've also made some adjustments to message instantiation. Signed-off-by: Stephen J Day <stephen.day@docker.com>

fs/p9p/new: implement several client methods Adds in stub implementations for several client methods, checking to see we have correct compilation of the various message types. We also add context support to control the lifecycle of the session object. We are getting closer to a working client and it is time to make a server! Signed-off-by: Stephen J Day <stephen.day@docker.com>

fs/p9p/new: Lock down encode/decode for 9p Among other things, this adds support for 9p encoding and decoding. We now have fully reflective message marshaling and unmarshaling. Other aspects of this commit include the code actually compiling and movement towards a testable interface. Signed-off-by: Stephen J Day <stephen.day@docker.com>

Both filesystem interfaces in master (fs & fs_tmp)