Added support for arbitrary URL endpoints.

Also added a WSGI factory function to simplify deployment.
Removed the simulator and cleaned up README.

Removed some superfluous stuff from the README file.
Consolidated CLI code into cli module.

Also added client_dev and server_dev shims to make it easier to
develop these programs. Updated the README.
Merge pull request #35 from jeromekelleher/client-urls

Added support for arbitrary URL endpoints.
Merge pull request #37 from jeromekelleher/cleanup

Cleanup: remove dead code and improve layout