Remove jQuery Dependencies

[asuh]

Removing jQuery dependency from main files since the rest of this is ES-2015 compatible

Document.readyState snippet added from this example:
https://www.sitepoint.com/jquery-document-ready-plain-javascript/#plainjavascriptreadyalternative

[QWp6t]

We decided against this and chose to use jQuery because jQuery is already a WordPress dependency and numerous WordPress plugins rely on it. That's not to mention that Sage comes with Bootstrap by default, which depends on jQuery.

See also: #1741

[asuh]

Right, I understand. The thought was that Sage provides the option to go with no CSS framework and the resources/assets/scripts files are for asset building. These are the only two files in /scripts that require jQuery so I submitted this to make it consistent with all other files in this directory.