Upgrade: address is_primary cleanup

Per discussions with Lobo & this thread

http://forum.civicrm.org/index.php/topic,11659.msg50019.html#msg50019

Include sql in the upgrade process to fix up people's databases where they have contacts with more than one primary address. This seems to be fairly common in 2.x databases and leads to a host of symptoms including incorrect search results which are hard to track down.