Tabs: markup upgraded to Foundation 5.3

Not sure when changed markup for tabs was introduced, seems like it was 5.3.

Besides of pure cosmetic change, it resolves HTML5 W3C validator error about missing required DD elements.

Rel. TS-81
Top Bar: SECTION.top-bar-section renamed to DIV

DIV instead of SECTION is not compatible with official Foundation markup - but having DIV gives better HTML5 W3C validator compatibility and removes 1 warning.

Rel. TS-63