Hopefully select the correct branch on startup

This removes the 'Avoid empty selection' attribute on the branch controller.
This should hopefully help with selecting the default branch correctly in
the menu.

Author: pieter

English.lproj/RepositoryWindow.xib

@@ -1750,7 +1750,6 @@ ELIAAAAAAAgACAAIAAgAAQABAAEAAQ</bytes>
 				</object>
 				<bool key="NSEditable">YES</bool>
 				<object class="_NSManagedProxy" key="_NSManagedProxy"/>
-				<bool key="NSAvoidsEmptySelection">YES</bool>
 				<bool key="NSPreservesSelection">YES</bool>
 				<bool key="NSSelectsInsertedObjects">YES</bool>
 				<bool key="NSFilterRestrictsInsertion">YES</bool>