Use Blaze._getTemplate to allow resolving into Blaze Components

[mitar]

With meteor/meteor@eff8016 there is now a Blaze._getTemplate function which is better to use than accessing Template[...] directly. The reason is that then packages like Blaze Components can override Blaze._getTemplate to provide resolving into components instead of bare templates.

I am not 100% sure if:

function () {
  return Template.instance();
}

is the best way to get current template instance, maybe it is available already somewhere in this code-path? But it should work this way as well. But I do not like access to global variables which Template.instance uses internally. So if you know of any better way to access current template instance at that code point, that would be great.

[mitar]

Closed in favor of #11.