Basic support for rpc over HTTP.

An extra 'http' flag is allowed on createserver which signals that the server accepts HTTP data over its socket instead of raw json lines, which is useful to allow, for example, javascript functions to POST calls.
There is no real HTTP layer error checking, which should be added.
The client side hasn't been changed to support HTTP.
Merge pull request #11 from nelisky/http

Basic support for rpc over HTTP.