This commit adds code to ensure that the values supplied by end
user for 'config' argument is not dropped in the create_vnf()
method. This scenario occurs in the case where end user supplies
values for both the 'config' and 'param-file' arguments.
Change-Id: Ied565217c2571283330f8f8cf62f76e2942826ba
Closes-Bug: #1493671
54c71bb9e3