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.