Faster cider-test feedback

When running tests via clojure-test-mode it was nice that you got
instant feedback while running tests. A failing test at the
beginning of a test run could already be taken care of while
other tests were still running.

With cider-test you get the test results after all tests have
finished. Would it be possible to stream the test results back
ealier, while other tests are still running?

For larger projects this makes quiete a difference, and I wonder
if there's interest in restoring this behaviour?

Otherwise I quite like cider-test.

Thanks again for this, Roman.