fix determining the response body tag name

[underoll]

Description

Looks like outputBodyDescriptor.elements[0].qname.name will never work, because it takes one level deeper then needed.
If it has the reason, i'd propose to return obj.Body as the result in case it is still empty after the three guesses.

Checklist

• New tests added or existing tests modified to cover all changes
• Code conforms with the style
  guide

[underoll]

Same is here https://github.com/vpulim/node-soap/blob/master/src/client.ts#L341
Cant imagine the reason for .elements[0]...

[dhmlau]

@underoll, sorry about the delay in reviewing your PR. There are test failures caused by your change. Could you please take a look if you're still interested in pursuing? Thanks.