don't remove title attribute for tooltips
fixes #6445
Merge pull request #6481 from pseidemann/patch-1

don't remove title attribute for tooltips
if no callback, don't try to call callback ya goof
Merge branch '2.3.0-wip' of github.com:twitter/bootstrap into 2.3.0-wip

Conflicts:
	docs/assets/js/bootstrap.min.js
only fire hidden once backdrop has been removed
remove prevent default on focus
add 2.3 changelog section
Merge branch '2.3.0-wip' of github.com:twitter/bootstrap into 2.3.0-wip
Merge branch '2.3.0-wip'
Merge branch 'master' of https://github.com/twitter/bootstrap into 2.3.0-durchblicker