grunt: compile with recess to fix whitespace and property order

bootstrap also uses recess, so the css in their /dist folder is bit different. with this patch, the output from `$ diff dist/css/bootstrap.css bower_components/bootstrap/dist/css/bootstrap.css` shows only the theme changes.
Merge pull request #8 from eins78/compile-with-recess

grunt: compile with recess to fix whitespace and property order