U2 Tooltips: Add basic MD-spec tooltips for U2
U2 Tooltips: Add basic MD-spec tooltips for U2

Easy to add - just create one on mouseenter and close() it on mouseleave.

foam-framework/foam,jlhughes/foam,jlhughes/foam,foam-framework/foam,foam-framework/foam,jlhughes/foam,foam-framework/foam,foam-framework/foam,jlhughes/foam