Various tooltips issues in backend

In Isis, when a tooltip contains some <br />, these are displayed instead of a newline.
Example: checkout an article and hover the icon lock in the article Manager as well as in the Popular and Last added articles modules in Control Panel.
In Hathor, it's even worse, we do not get bootstrap tooltips and hover on the Featured star icon or the lock goes havoc.

This patch implements html: true for the bootstrap tooltips and popover, changes  JGrid to use 
JHtml::_('bootstrap.tooltip');
instead of
JHtml::_('behavior.tooltip');

and adds the necessary css for Hathor, correcting all tooltips there.