Properly reference jquery as acquired.
Whitespace cleanup
no need to duplicate extendMetadata onto settings

You can access the method just fine by calling
require('metadata/metadata-plugin').extendMetadata().
rename _init to initEditable.
Add a configurable metadata initialisation callback

This allows the plugin to fetch it's metadata from elsewhere. It's useful,
and due to the persistent fighting with race conditions where we cannot
call extendMetadata() because the plugin isn't initialised yet, I figured:
Add a way whereby the plugin can do this when it's good and ready.
Merge pull request #149 from oerpub/metadata-plugin-fixes-episode1

Metadata plugin fixes