update phantom-compatible test runner to work with recent slimerjs (gh-10)
(ref https://github.com/laurentj/slimerjs/issues/223)
* support slimerjs "officially"
* use p.evaluate instead of p.evaluateJavaScript
  (The semantics of the latter appear to differ between phantomjs and slimerjs;
  the former is cleaner anyway)
0.3.3-SNAPSHOT
drop back one rev on core.async (pending https://github.com/clojure/core.async/commit/422f8b25f0c4d5e3aea5113436c735e553422be7#commitcomment-8949149)