[BUGFIX beta] Implement public module API.

[rwjblue]

• This replaces the public module API from ember-cli-shims. These shims have been removed from ember-cli-shims in Remove ember-data shims. ember-cli/ember-cli-shims#38.
• Adds shims when define && define.petal (which is set by loader.js) is present.
• Remove old addon + blueprint.
• If bower.json includes ember-data a warning will be issued, and that
  version will be used.

[bmac]

LGTM 👍

[rwjblue]

Updated again, added the following:

• Remove old addon + blueprint.
• Use bower version of ember-data if present.

In order to keep backwards compat, we must honor the version of ember-data that is present in bower.json (even though it is not needed). This is due to the fact that many people update the package.json and bower.json versions of Ember Data completely independently.

If bower.json includes ember-data a warning will be issued, and that version will be used.

[rwjblue]

Added two more changes:

• Do not ENABLE_OPTIONAL_FEATURES in consuming applications. -- We were previously setting EmberENV.ENABLE_OPTIONAL_FEATURES = true in consuming applications, which is generally not what we want. This updates to ensure that only the internal addon development is tweaked/changed.
• Provide helpful warning for using older ember-cli-shims. -- As reported with https://github.com/jcope2013/active-model-adapter-ember-cli-2-beta-issue, ember-cli-shims@0.1.0 does not play well with Ember Data 2.3, this warning helps folks know to update.

[bmac]

Thanks @rwjblue.