minor bug fix
ignore records with no serial# and no asset_tag#
Make sure service records with null type are returned
make it possible to specify the domain to use with ProvisionGET
Fix handling of the date_created attribute for devices

Explicitly set the date_created field for system POSTs and new entries
created via ProvisionGET or PcmProvisionGET.

Prevent date_created from being set by the user as part of a PUT or POST
request.