adding theme and vis classes to chart body in template
Updated the Unit-tests to test the oEmbed functionality, as well as testing publish and cleaning up after running.
Relaxed a type-requirement in a equality-check such that users can be deleted via the API.

The API will always receive the user-id as an string, but it is stored as an integer, so you would end up having 1 === '1', which failed.
Added a global hook, GET_PUBLISHED_URL_PATTERN, so plugins that provides new published-urls can register for oembed.
Removed oembed-plugin from core, as it's now has its own repo
Removed hook-definition only used by the oembed-plugin
Commented out test-case for the oEmbed-endpoint since it will be a non-default plugin.