Add ClojureScript support

I experimented with replacing valip with validateur in [modern-cljs guide](https://github.com/magomimmo/modern-cljs/blob/master/doc/tutorial-13.md#the-server-side-validation) and everything went fine.

So I added testing under ClojureScript. Hope you like the idea. Feedback is highly appreciated.

P.S. There is one failing test at the moment under cljs and I'm not sure how to properly fix it.

``` clojure
FAIL in (test-format-of-validator-with-optional-message-fn) (:)
expected: (= [false {:id #{[:format {:id "123-abc"} :id ["abc-\\d\\d\\d"]]}}] (v {:id "123-abc"}))
  actual: (not (= [false {:id #{[:format {:id "123-abc"} :id ["abc-\\d\\d\\d"]]}}] [false {:id #{[:format {:id "123-abc"} :id ("/abc-\\d\\d\\d/")]}}]))
```