add support for SOAP Web Services (xml payload)

[rafaeltuelho]

Would be nice have the ability to consume legacy SOAP WS and map xml response to JSON. There are some JS client implementations to consume SOAP WSs:

• https://github.com/vpulim/node-soap/
• http://cxf.apache.org/docs/javascript-clients.html

One approach is to consume the WS, convert the XML structure response to JSON and them using the existing mapper tool.