Use Ember.Handlebars.get internally

`Ember.Handlebars.getPath` emits deprecation warnings if `ACCESSORS` is
set to `1.0`. `Ember.Handlebars.get` is new and always has 1.0
semantics. (It uses `Ember.getPathWithoutDeprecation`). Thus, we can
always use the `.get` version safely and avoid the warnings.
Merge pull request #27 from zendesk/james/handlebars_get

Use Ember.Handlebars.get internally