add support for data-tag-name attribute on handlebars script tag

[pangratz]

Inspired by question http://stackoverflow.com/questions/8629287/how-do-you-specify-the-tag-name-for-sproutcore-emberjs-inline-script-templates I've added support for data-tag-name which defines the tagName on the view created for a handlebars template.

Example:

<script type="text/x-handlebars" data-tag-name="h1" >
    Foo
</script>

which outputs

<h1>Foo</h1>

[wagenet]

Is this something we can write tests for? I can't recall if we have tests for loader.js but if we do we should definitely add to them. If not, I guess you're off the hook, though we should still write tests.

[pangratz]

How can I test a custom HTML page with QUnit?

[wagenet]

I'm not expecting that you'd be able to make a full integration level test, just that you may be able to test some of the pieces.

[pangratz]

Hmm, kind of difficult with how the Ember.Handlebars.bootstrap looks like https://github.com/emberjs/ember.js/blob/master/packages/ember-handlebars/lib/loader.js

Do you have any suggestions?

[pangratz]

OK, I've added some tests for the data-template-name and data-tag-name features.