Initial CSS support (#1636)

I wanted to see how hard it would be to add support for CSS inside of prettier. Turns out, it's not that hard. I spent a few hours printing post-css values and getting all the stylefmt unit tests to not throw.

.gitignore

@@ -2,4 +2,6 @@
 npm-debug.log
 /errors
 /test.js
+/test.ts
+/test.css
 /.vscode