Incorporate a Bootstrap implementation

[rtblair]

As @CeciliaCY mentioned at the agency demo, several agency applications built on Microsoft's stack leverage Bootstrap on the front end.

In order to create a more consistent UI across ITD products, a Bootstrap-compliant implementation strikes me as a valuable step.

[andycochran]

Tho there's not a direct 1:1 mapping of components, a step towards using Bootstrap to incorporate the guide's basic styles would be to create a scss/_variables.scss for theming Bootstrap.