Deprecate unused initializers

[bmac]

Ember Data has 4 initializers that it supports for legacy reasons but otherwise do nothing. https://github.com/emberjs/data/blob/master/tests/ember-data-initializers.js#L18-L40

@rwjblue suggested that it may be possible to deprecate them by "hook[ing] into the DAG map that is used for initializers and see if anyone depends on it"

[wecc]

Link is gone, should be these:

https://github.com/emberjs/data/blob/master/app/initializers/data-adapter.js
https://github.com/emberjs/data/blob/master/app/initializers/injectStore.js
https://github.com/emberjs/data/blob/master/app/initializers/store.js
https://github.com/emberjs/data/blob/master/app/initializers/transforms.js