Removing support for libraries API

Problem/Motivation

The libraries API module
was supported in D7 and never really got adapted to the D8 implementation.

I'm not aware of any other module providing a jstree libraray.

Proposed resolution

Remove the obsolete hook https://www.drupal.org/project/libraries and other code related to libraries api.

API changes

Any libraries API jstree resource will no longer be used, and this module will fallback to the CDN usage.
Still you have the option to install jstree according to the instructions on this modules project page.