New Permissions

Although it appears to be having no negative affect so far, it's probably best to add the new _"clipboardRead"_ and _"clipboardWrite"_ [permissions](http://code.google.com/chrome/extensions/manifest.html#permissions) added in [Chrome 13](http://code.google.com/chrome/extensions/whats_new.html#13) in order to access the necessary `document.execCommand` commands (copy, cut and paste).
