caea075deb
This change has two parts. First it allows a user to define an argument to the role that is wraped around diskimage-builder to add an optional environment variable of DIB_RELEASE to the build process. Secondly it sets a default for the test sequence to utilize debian jessie for the builds to stabilize the non-voting CI test. Change-Id: Ifbc0f1ce42f3ab9ec73951a813ab0c4a38639550 Closes-Bug: #1521313