Separate the generated css to it's own file and avoid versioning it in github

Style.css is required by wordpress since it's beginning comment holds the theme's information. But, if we're using grunt compass to generate the style.css, the rest of the file is generated css which is an artifact. The information is already contained in the assets/scss/style.scss file. 

I propose we have grunt compass generate assets/css/style.css and have ./style.css include that. that way ./style.css just has the Theme information part and the generated css is .gitignored. 

This does not affect someone who wants to just code in css. They can edit ./style.css at will.  They would just need to avoid running grunt compass or make sure that they don't collide with asssets/css/style.css for an imported file. That seems unlikely or easily fixed.

This does mean an extra step before installing this theme,  and that's running grunt compass once. But since that's the point of this setup, that seems acceptable.