VPNaaS Cisco REST client enhance CSR create

VPNaaS Cisco REST client enhance CSR create

For the create of the REST client object that represents a Cisco CSR,
all of the info needed were passed in as separate parameters. This
change just uses a dict instead, so that additional parameters can
be added w/o changing the API.

Updated the currently unused UT module, just so that it can be used
locally and stays up-to-date until it can be converted to use the
new requests-mock package.

Change-Id: I5d4f439cc7ffe125cea9ed3407b70645587a739a
Closes-Bug: 1336478