Add Sass and Specljx

This is likely not ready to merge.  

This PR integrates Sass in a comparable way to Less.  However, the sassc API changed with 3.0.2 and lein-sassc is broken (my fork is not pushed to clojars, nor have my changes been merged into the canonical).  More conditionals.

This PR also integrates speclj / specljs but does not give additional test framework options.  Even more conditionals.

That said, the sass autocompilation works for me, as does autotest for clj and cljs, so I'm opening this PR to get some feedback.