Set the zone if specified in the SOAP request

https://bugzilla.redhat.com/show_bug.cgi?id=1135627

The required zone can be specified in the "parameters" being passed
to CreateAutomationRequest. The attribute name is called miq_zone
Is this validation needed?  In the dialog do we provide a pulldown of zones?  I don't know that you can delete zones so it would be preferable to not allow them to enter the zone name free form if we don't have to.