Add On hold field for postal addresses

From SE: http://civicrm.stackexchange.com/questions/681/what-are-best-practices-for-bad-postal-addresses

There is a good work-around currently - http://civicrm.stackexchange.com/a/689/40

Lobo "would structure this similar to the "on hold" for email addresses, and then have the mailing label and other workflows respect the property. Integrating this with the USPS (or other providers) address cleanup/validation would make it even better." I like the idea of having a reason field for why the address went on hold, since this will allow the address to eventually be removed. (One client of mine has a field for this with values including: Returned Once, Returned Twice, Moved, ....).