UP-4008 / IP:65: Reapplied Universality functionality to Respondr

Moved relevant CSS from layout-portlet.css and portlet.css (universality) into the selectEntities.jsp in order to use the same functionality for categories/groups.Also updated markup to include Bootstrap classes for mobile-responsiveness. Added a few general overrides for Respondr into content.less.
@doodelicious and I just discussed moving these styles to a separate CSS file and linking it in because (1) there's a large number of definitions and (2) they don't use the portlet namespace or any dynamic content... they're completely static.

Incoming.