mv HTTPMsg to AsyncMsg, add 'raw' method

Convert sh/wm7d command to AsyncMsg.
Modify all the HTTPMsg converted cmds to use AsyncMsg.

Add a 'raw' 'telnet' handler. This allows one to query things with command
prompts or stuff that isn't a HTTP server. But it ain't always easy. See the
messing around in sh/wm7d I had to do, to get something that is stable given
that the thing that I am looking doesn't have a \n at the end.

It's just a prompt.