Adds in the mute feature.

- The current mute feature works after the loader has completed, but not
  on load.  This is causing certain machines to play high pitched noises
  upon load.

- I've done some housekeeping in this commit as well to eliminate global
  variables within the module.

The `JSMESS.ready` function now passes the `Module` object as an
argument.
Merge pull request #19 from tbranyen/fix-mute

Adds in the mute feature.