1) Ability to add extra headers to the client request + two tests
2) Test to ensure that client has lastResponse and lastResponseHeaders
after it returns
Issue: Requests that included compex types led to invalid request XML.

Fix: Pass namespace and xmlns when generating child node XML, otherwise generated XML nodes will have no values.
Add check if namespace string contains ":".
Merge pull request #301 from ankush-garg/headerBr

Ability to add extra headers to the client request and tests