Run tests against multiple versions of Ember

[GavinJoyce]

/cc @rwjblue @stefanpenner

This adds support for running tests against multiple version of Ember and closes https://github.com/eviltrout/ember-performance/issues/59.

The TestSession now contains an array of TestGroups which have an associated Ember version and an array of TestItems.

Test results are now presented as ascii text only (closes https://github.com/eviltrout/ember-performance/issues/62):

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I'll create some follow-up issues once this has merged:

• update app to use ember-cli (https://github.com/eviltrout/ember-performance/pull/64)
• better results UI (group tests so that they can be compared easily)
• support multi submit results (a single result can still be submitted)
• Add Ember 2.1.0 (https://github.com/eviltrout/ember-performance/pull/63)
• create issue for large error % in complex list rendering test
• truncate long test names to avoid dodgy result formatting
• adds graphs

[rwjblue]

This is looking really good, thanks for putting the time into it.

RE: the checklist above, let us know when you think this is ready to land and I will review again. We can make new issues for any remaining items (you mentioned some might be separate PR's).

[stefanpenner]

wohoo!

[GavinJoyce]

@rwjblue this is ready for review, thanks

[eviltrout]

Looks fantastic to me too! Thanks so much for this feature.

[GavinJoyce]

I've got a couple of PRs backing up, it would be great if someone could review this

[rwjblue]

Sorry for the delay, got a bit behind the last couple days.

[GavinJoyce]

No worries, thanks!