Add missing mobile layout options

Problem/Motivation

One extremely useful feature of bootstrap grids is wrapping grid items on smaller screens.

There currently are no layout options to take advantage of this feature. It's also not readily apparent that is something that can be added by a site builder through the layout options feature.

Proposed resolution

Add the most obvious layout options to the install configuration

• 4 column wrapped to 2
• 6 column wrapped to 3
• 12 column wrapped to 6 and 3

Also add in the basic layout options for 12 column which are missing entirely.