Ignore the sass-cache directory
Ignore the node_modules required by Grunt
Add missing CSS/Sass and the tools for building it

Much of this should be in a third-party repository for building the
Texas Tribune Sass.  Unfortunately, most of our Sass is stuck in a
private repository.  Much of this was copy-n-pasted directly out of that
repository.  Ideally, it will be removed and/or streamlined in the
future once that code is public.
Add some rudimentary docs on using Grunt
Initial port of all of the Sass for explorers

This renames the `.explorer` class to `.dataviews` (hopefully a
temporary thing) and then breaks all of the individual components and
pages out into their own files to make it a little easier to navigate.
Wrap in main app.css in block so it can be turned off
Swap out to use the new body.dataviews class
Bring in the current .gitignore from the templates
Remove an extraneous selector
Switch to the current Gruntfile.coffee
Add missing reference to compass and switch to bundler based install
Merge pull request #2 from texastribune/add-sass

Add missing Sass