Does not respect `ember-cli-htmlbars`' `wrapper.cacheKey()`

[amiller-gh]

Expected Behavior:

Both ember-cli-htmlbars and ember-cli-htmlbars-inline-precompile should allow plugins to provide the same caching scheme.

Observed Behavior:

ember-cli-htmlbars allows plugins to provide a custom cache key if the addon's baseDir() is not sufficient: https://github.com/ember-cli/ember-cli-htmlbars/blob/master/ember-addon-main.js#L121

ember-cli-htmlbars-inline-precompile does not allow for this: https://github.com/ember-cli/ember-cli-htmlbars-inline-precompile/blob/master/index.js#L117

Proposed Fix:

Port ember-cli-htmlbars' plugin cacheKey() method to ember-cli-htmlbars-inline-precompile.

[rwjblue]

Yep, totally agree

[rwjblue]

This should be resolved now (see #298, but this library is being deprecated completely in favor of "just using ember-cli-htmlbars").