Update to version 0.9.13

Better container reference #1151
Fix issue when destroying last choice #1149
Use selectedIndex for tracking change events. #1147
Better IE Disabling #1144
Dropdown use css positioning for top position #1143
Fix bug when deleting last item #1142
Percentage Width Support #1141
CSS Centering Fix #1120
Use New CoffeeScript #1125
Chosen License #1111
Update placeholder text with ``liszt:updated`` #1107
Fix strange event bubbling #1055