Support for left-opening dropdown submenus

Adds a new class called .dropdown-submenu-left. It is useful when you
have a .pull-right DropDown that has submenus. Without this, the menu
opens left past the page boundary, which can trigger the scrollbars and
cause other nastiness.
change tooltip/popover html default to false for xss safety net
Merge branch '2.1.2-wip' of github.com:twitter/bootstrap into 2.1.2-wip
reverting d797a5fbd7dd883a09bf00e516e0bd509c898f53
change tooltip/popover insert strategy
remove modal-open class
hopefully resolve z-index headaches
update docs for tooltip html + the dropdown methods api
check affix pos on clicks - use timeout for clicks which scroll
Use paginationActiveBackground var to finish fixing #4295
dat new kippt hotness
Merge branch '2.1.2-wip' of github.com:twitter/bootstrap into 2.1.2-wip
bind data-api events to document instead of body to allow body replacement
Fixed bug in dropdown toggle where menu would only clear on the first drop down
Making modal work with max width 767px - fixes #4860
Fix for #4550

Also fixes dropdowns hiding behavior for case when two or more dropdowns
with [data-toggle=dropdown] exist on the page
don't wait for ready when binding events to document
fixes #5334: html snippet comments
clean up emphasis docs text
fixes #5360: typo in tables docs
add link to examples on index page; add back narrow marketing page and signin page examples
Fix for #5362

Fix for issue [5362](https://github.com/twitter/bootstrap/issues/5362):
tab events fired on wrong dropdown anchor.