Move natmus javascript file to scripts folder

This is to use the compile settings already in Gruntfile. LP#15202477
Prevent horizontal scroll on mobile devices

The overflow-x was present on mobile devices. It may have to do with the body tag being relative displayed. Hide overflow-x on main wrapper element fixes this.

Also set initial scale to 1.0 for the viewport.

LP#15202477
Make desktop grid for assets

We use standard bootstrap grid to create a two column presentation on desktop while just stacking the elements on phone and tablet sized devices. LP#15202477