Ember 2.0 support

[GavinJoyce]

closes #51

This updates the tests to run on Ember 1.11 -> Ember 2.0. I've implemented a new RenderTemplateTestClient which allows for simple tests such as:

(function() {
  var template = "hi {{name}}";

  RenderTemplateTestClient.run({
    name: 'Render simple attribute',

    setup: function() {
      this.setupTemplateTest(template, { name: 'Ben' });
    },

    reset: function() {
      this.hideComponent();
    },

    test: function() {
      this.showComponent();
    }
  });
})();

I've dropped versions earlier than Ember 1.11 as they would require separate templates.

[GavinJoyce]

this should be data=item.a

[GavinJoyce]

I've gathered results from before and after this PR to ensure that we're still capturing the slowdown and subsequent speed improvements in initial render performance:

https://docs.google.com/spreadsheets/d/15MPfzCncD_PvM-nmfdrA-_UsUzNpAVV9pFkt3wU5rBo/edit?usp=sharing

The new tests seem to be capturing this correctly (master on the left, #52 on the right):

[GavinJoyce]

/cc @eviltrout I've got some time this week to continue to work on ember-performance. It would be great if you could take a look at this, thanks

[eviltrout]

This looks excellent, I will merge now :)