Model tests aren't very grep-able

Hey there, I opened up a [pr on ember-data](https://github.com/emberjs/data/issues/4555) because I noticed that when selecting a single test in the browser all the issues that start with `Unit` show together, rather than showing only `Unit | Model | ModelName`.

I think it has issue with the spaces. Was just taking a look through the code here, and was trying to think of a way to make the [separator](https://github.com/ember-cli/ember-cli-test-info/blob/master/index.js#L13) configurable by consuming addons.

Or maybe just change it to something that is still grep-able? Not sure what the best way to go about that would be.

@stefanpenner any thoughts?