Refactored mongo calls.

All database calls are now being handled by the robot_db server.
The queue_listener and registration_worker have had all references
to mongo removed and replaced with calls to robot_db.
Made the robot_control page dynamic.

Two major things have happened to this page: 1) it is now rendered
via the mustache engine so that we can pull the current registered
robots from the db and display them in a drop-down (rather than
an input box). 2) The javascript has been abstracted and taught to
deal with the options of the select box rather than the text field.
Taking more care when waiting for commands.

Added code to protect when the client drops off expectedly. We now
have enough traps to ensure that the robot will unregister if the
socket becomes unusable.
Pulled the robot_control page to a new module.

This allows a nice, clean separation between xhr commands and
templated pages. At least I think it does.
Switched over to the event-based model for ws.

If JSON is pushed up to the client, you can clean up the client to
expect very specific events rather than a general message that has
to be parsed out on the client. Sort of cool.
Cleaned up the console log a bit.