Allow animateplus as an EmberJS addon

[jmurphyau]

This adds the infrastructure required for animateplus to work as an ember addon

[jmurphyau]

I'm pretty sure this all looks good but I don't have any examples of taking an existing npm package that wasn't an ember-addon and add on everything required to make it an ember-addon..

There is an example of taking an ember-addon npm package and repurposing it as a JSCS preset while allowing all the ember-addon stuff to continue to work - I used this as a reference.

@bendc If you'd rather not merge this in and have it seperate thats fine too I'll just create this as an ember-addon that uses animateplus as a dep. (:

/cc @rwjblue @jasonmit - is there any chance you guys could give this a quick look over?

@rwjblue I stole the general idea and the package option "ember-addon/main" from you/ember-suave.

@jasonmit I used your index.js as the basis for the one I created.

• Use 'treeForVendor' to put files in the vendor/<addon-name>/ directory available for the addon (so they can be used in the included hook via app.import)
• app.import the files

[rwjblue]

:+1: - Seems good to me.

[bendc]

Thanks James! I'd vote for a separate ember-addon as I'm not qualified to judge this PR and I'd rather not endorse something I can't judge properly :)