* Issue was that region server was silently dropping an XmlException caused by trying to deserialize the blank asset service response
* So make asset service return http status NOT FOUND rather than OK in accordance with REST
* and interpret this correctly in the async response so that a null object is sent back
* This means that this fix won't be active until both region simulator and server reach this revision
* If an oar save fails to get responses to all asset requests to the asset service then timeout after 60 seconds
* Timeout executes abort, since missing assets in an OAR seems bad
* This means that oar saves won't permanently hang and instead can be retried if something goes wrong with the asset service
* This is not a solution to mantis 3714. Hopefully a fix will be along shortly since I can now consistently reproduce that problem
