Adds encapsulation control to the client

https://review.openstack.org/#/c/108795/ adds the requirement
to encapsulate messages in JSON objects in API v1.1

This change adds that control to the Zaqar client maintaining
backwards compatibility with v1

Change-Id: I1723b843320ebcf2722fb4f6fcaaa6e1c63248e9
Merge "Adds encapsulation control to the client"