Use Ember.Handlebars.get internally

@shajith @chrsjxn

`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.