Removing unused modules of the babel library

[Lucas-Code27]

Fixes #3607

Changes Summary

• Used npm to uninstall all unused babel modules as requested in Do we really need Babel?  #3607
• Remove core-js
• Removed references in build config

This pull request [ is ] ready for review.

[RMcNeely]

Do we need to change the Gulpfile at all? It's been a minute but I assume that's where those packages were being used?

I'm away or I would grep for them myself

[Lucas-Code27]

I checked conflicts and I'm pretty sure the entire babel library is used just for a file called "webpack.config.babel.loader.js" to load the _scripts folder and it only needed babel loader which requires the entire babel library so I believe if a solution is found to load scripts without needing the babel library then we could remove babel

[RMcNeely]

Still WIP, needs a solution for hashing scripts

[lewisgoddard]

New supported browser list:

Browser	Since
Chrome	55 (2016)
Firefox	52 (2017)
Safari	10.1 (2017)
Edge	15 (2017)

Drops support for IE 11 and any browser older than ~2017.

[RMcNeely]

Finally got time to actually run this. Gulp works good and I can run the dev server 👍