fixes #5542: move '.hero-unit p' font-styles to '.hero-unit' so they apply to all elements, including ul and ol, within the component.

add missing icon class definition for navs:
'[class*=" icon-"]'

P.S. Sorry for 2 pull requests with the same problem..

add missing icon class definition for buttons:
'[class*=" icon-"]'

Also fixes dropdowns hiding behavior for case when two or more dropdowns
with [data-toggle=dropdown] exist on the page

remove modal-open class
hopefully resolve z-index headaches

fixes #5102, #5166, #5194, #5205: add overflow: visible; to .nav-collapse.collapse so that dropdowns overflow correctly in the navbar in IE7-8