Add Sass/Scss support

[MoOx]

The sass/scss syntax embed a lot of things. It works great with a theme I made based on Monokai https://github.com/MoOx/sass-prism-theme-base
Maybe I should make a PR with the CSS generated by this theme.

[MoOx]

I'll update this PR with a lighter version as you recommend

[MoOx]

I've try something, but it fails since the order of the declaration are important. Using extend() we can't control order of the parsing, so some rules are not parsed & this doesn't take effect. That's why I overwrite a lot of thing.
Beside that problem, I understand that I've put too much thing, non especially sass/scss related, but this is another issue :)

[LeaVerou]

You can use insertBefore for that, look here for an example: http://prismjs.com/components/prism-javascript.js

Regarding not including too many tokens for CSS, that was a conscious choice, since most use cases don't need that kind of granularity.

[MoOx]

Oh sorry, I don't look closer enough. This is just what I need. Your highlighter is so well done.

[MoOx]

Completely rewrote. Lighter & inherit from CSS. Tell me what you think about that now.

[MoOx]

What about this PR ? :)

[LeaVerou]

Gah, the pull request cannot be merged. Could you please submit a new one? Sorry I took so long, it's my fault :(