Use node-watch instead of fs.watch
fs.watch caused problems when text editors output temporary files.
This commit changes the myth executable to use node-watch rather than
fs.watch, allowing myth to honor the --watch flag when the file is
edited with a text editor that outputs temporary files (e.g. Vim).

Fixes #22
Merge pull request #24 from shanepelletier/master

Use node-watch instead of fs.watch