A quiet reporter for karma.
The builtin progress reporter is nice, and it maintains a running
status line for each browser, like:
PhantomJS 1.9.7 (Linux): Executed 27 of 27 SUCCESS
This is cool, but if you're not running in a real terminal (e.g travis-ci), you'll get status lines smattered across your logs.
This reporter only prints output from the browser, and adds none of its own.