Make image prefix configurable.

Adds a new parameter to docker.gradle `dockerImagePrefix` which specifies the PREFIX part in the following format: {REGISTRY}/{PREFIX}/{IMAGE}:{TAG}. This used to be hardcoded to "whisk", e.g. whisk/controller.

Implements a parameter for ansible to pull an image prefixed by "docker_image_prefix" (PREFIX in the following format): {REGISTRY}/{PREFIX}/{IMAGE}:{TAG}. Was previously hardcoded as "whisk".

Writes the parameter into whisk.properties and makes the invoker pick it up for spawning containers.

Add different tag in travis to flesh out problems.
22 files changed