Make sure that all Ember modules are imported form utils/ember.js

[mansona]

The utils/ember.js file intends to provide a single place to import all modules from Ember.js but unfortunately this has bled out to the rest of the repository. We should fix this (and consider adding a custom lint rule) so that all of the switching around module systems can be done in one place (i.e. AMD vs real modules with import())

You can see some of this work in #2625

you can see a great example of this problem in this one change https://github.com/emberjs/ember-inspector/pull/2625/files#diff-44e94af2ff304408b73894b1304fb9d10fb0f95a13639a571cb695774faeb9d5

I.e. you should not ever be trying to require a module outside of the utils/ember.js file