Use custom reporter instead of cljs.test one

[arichiardi]

I have noticed reading the doc of cljs.test that you can basically use a custom keyword for reporting:

You can plug in your own test-reporting framework by specifying a :reporter key in the test environment. It is normally set to :cljs.test/default. Set this to the desired key and supply custom implementations of the "report" multimethod.

It is probably a nice idea to have something more pluggable and/or modular.

I am playing around with this as we speak 😄