Fixed a bug where if the caretContainer contains html and the user presses backspace, the non editable sibling element is deleted rather than the letter right after user's cursor.
Added extra unit test to make sure when the user add text right next to a non editable token, and then pressing backspace, the last char only is deleted.
TINY-98 Fixed bug in Firefox causing non correct delete of nonEditbale token.
Fixed unit test for IE8-9-10 on backspace for the nonEditable plugin
Fixed test checking only for IE10
Fixed test utils fake backspace in IE
changelog for non-editable bug where backspace deletes too much text