Include/Expand Flexible grid templates plugin in Tiny

BS grid is a atto plugin that enables 1-click bootstrap grids to be inserted into user generated content.

Why is this important?

• tables aren't always accessible and bootstrap elements tend to be more accessible to adaptive technology (screen readers)
• collapsible structures for mobile
• HTML5 best practices

Ideally, we'd have other Bootstrap elements available within a single button as well (button, accordion, card, ect) but layout structures are one of the things our users struggle with constantly. For example, how else would a novice user create a flexible mobile friendly 2 column layout in a simple page activity? 

This request should be attached to the epic MDL-75926.