modify EiEventService

1) setting request in VenTransactionLog
in function handleOadrRequest(OadrRequestEvent oadrRequestEvent),
venLog.request should be set
because constraints of VenTransactionLog.groovy does not permit request nullable.
This fix https://github.com/EnerNOC/oadr2-vtn-new/issues/21 .

2) check 'errors' contains what kind of object
in function processEventResponses( OadrCreatedEvent oadrCreatedEvent ),
I got groovy.lang.MissingMethodException when I sent Created event.
Object kind in variable 'errors' should be checked.