CA-106080: DB upgrade rules update license_params.sku_type

The previous upgrade rules for the DB only modified license_params.edition
(advanced,enterprise,platinum -> per-socket, enterprise-xd -> xendesktop). We
also need to modify sku_type, because v6d will return current_edition =
previous sku_type on the case of an expired license. This is an edge case for
when a license expires just prior to a host upgrade, with no valid licenses on
the license server after upgrade.

Signed-off-by: Mike McClurg <mike.mcclurg@citrix.com>
CA-106080: Guard List.assoc "sku_type" license_params with mem_assoc

From code review on pull request #1226: since sku_type is a key that's returned
from v6d, and not present natively in xapi, we need to test that sku_type is
present before calling assoc on license_params.

Signed-off-by: Mike McClurg <mike.mcclurg@citrix.com>
Merge pull request #1226 from mcclurmc/ca106080-upgrade-enterprise-xd-master

CA-106080: DB upgrade rules update license_params.sku_type