Clean up output of css selectors via placeholder classes

A ton of classes like rs-link and rs-nav were being snowballed into a messy set of rules. This cleans up 90ish percent of that. I'd like to get this in before I add the rs-section classes and fallbacks for the old classes.

Before:

- Total rules: __522__
- Total selectors: __2190__ 

After:

- Total rules: __525__
- Total selectors: __942__

Used this snippet get the above info: https://gist.github.com/eddywashere/7575099