Added module definition pattern to plugin

Per request for package.json: https://github.com/razorjack/quicksand/issues/120 and https://github.com/razorjack/quicksand/pull/124.

I also wrapped the plugin in a module export to allow for use with CommonJS (browserify) and AMD (require).  I made no changes to the actual code.  Only a proper wrapper.

I realize my browser removed the whitespace at the end of lines.  I can submit a new pull-request without them if preferred.