Change _normalizeTypeKey to defer normalization to the container

[bantic]

There are some failing tests and some additional work to do.
The issue is that in unit tests for ember-cli for models with dashes and
when using an adapter, the model's typeKey is normalized to camelCase
but store.modelFor(camelCasedName) will fail.

For example, with a model class 'ssh-key', create a record using the
string 'ssh-key'. This will work fine because the store will call modelFor('ssh-key'). This returns the correct model factory and it has the side effect of setting typeKey on that factory to sshKey.

Later, when saving that record, the store will call Adapter.createRecord which starts out by calling
store.serializerFor(type.typeKey). The store's serializerFor method passes this same typeKey (sshKey) to store.modelFor. But store.modelFor('sshKey') will fail because it will call container.lookupFactory('model:sshKey') and find nothing.

The call to lookupFactory('model:sshKey') will fail in the test because the test's container's normalizeFullName method is this:

function (fullName){
  return fullName;
}

When running an ember-cli normally (or when running an acceptance test), the container uses the ember-cli resolver and its normalizeFullName method becomes this:

function (fullName) {
        if (resolver.normalize) {
          return resolver.normalize(fullName);
        } else {
          Ember.deprecate('The Resolver should now provide a \'normalize\' function', false);
          return fullName;
        }
      }

In this case, resolver.normalize will return the same value ("model:ssh-key") when it is passed either "model:sshKey" or "model:ssh-key", so the app's store.modelFor('sshKey') and store.modelFor('ssh-key') return the same thing.

There's a sample ember-cli app showing this behavior. The important parts are in this commit. The failing test code looks like this:

  import {
    moduleForModel,
    test
  } from 'ember-qunit';
  import Ember from 'ember';

  moduleForModel('ssh-key', 'SshKey', {
    // Specify the other units that are required for this test.
    needs: ['adapter:application']
  });

  test('it can be looked up', function() {
    var store = this.store();

    var sshKey;

    Ember.run(function(){
      sshKey = store.createRecord('ssh-key');
    });

    return Ember.run(function(){
      return sshKey.save();
    });
  });

Screenshot of the failing test in the ember-cli app:

cc @mixonic

[stefanpenner]

ping?