scope clojurescript.test dependency to test

1. I don't think we need to distribute the test lib we use along with
our binary/cljs source
2. If we leave this in the default scope, it produces dependency
conflicts with other libs that depend on older versions of
clojurescript.test. These conflicts are typically visiable via warning
messages after running `lein deps :tree`
Merge pull request #1 from kbaribeau/master

scope clojurescript.test dependency to test