Gracefully handle output during tests

[SevereOverfl0w]

2 known things can cause messages containing 'out' when running tests:

1. Exceptions during the require phase of the test operation will cause exceptions to be printed
2. Any println, etc. inside of the test itself.

A cursory play with emacs showed that this on a per-assertion is lost when using cider. I suspect it is expected to show up in the REPL or something, but vim doesn't have that.

I can spit the outputs to the top of the output when running the tests, but they won't be interweaved with the assertions that created them. This may warrant some upstream cider-nrepl changes, but it may be hard to achieve that without breaking the workflow of existing cider.el users.