<img /> tag with `height` attr are not responsive

namespace the events for popover/tooltip

move from downloads.html to customize.html to better match purpose of page, fix up customize page layout to match other docs, link style refinement to jumbotrons

fixes #4102: properly round top left corners of .table-border with caption/colgroup; also fix css tests page layout and footer

Conflicts:
	docs/base-css.html
	docs/templates/pages/base-css.mustache

Moved JS to bottom on extends page

fix dropdown vars and make hover state be link color again, add gradient to dropdown link hovers, fix caret positions and active states on nav tabs, tweak nav link padding

Conflicts:
	docs/extend.html
	docs/templates/pages/extend.mustache

Moved JS to bottom as per best practices