FIXED “Fails due to case-sensitive REL attribute condition”

I'm using livereload via `node-livereload` and/or `guard-livereload` on a legacy Rails project running the `asset_packager` helper (before Rails had this built-in). It took me forever to figure out that `livereload.js` was actually working, but checking for linked stylesheets using `xxx.rel === 'stylesheet'`, which failed to trigger because the old asset packager was writing its tags using `rel = "Stylesheet"`...

I've fixed this in a feature branch, and will submit a pull request shortly.

Btw: I'd already fixed this in these guy's versions of `livereload.js`:
https://github.com/guard/guard-livereload/issues/118
https://github.com/napcs/node-livereload/pull/28
but thought it finally better to fix the source...