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
@jrafanie 
The zone name in this case is coming from a SOAP request and is not picked by a user from a drop down. so it could by just any string so we need to validate that it was valid