This PS updates the values file layout for images to allow simple
parsing of the images in use by charts, allowing them to be queried
and modified much more simply. By moving the image tags to a 'tags'
key, we can extend the options used simply to accomodate extra
options simply (eg prefixing the tag for use with an internal
registry) or pre-pulling the images to reduce chart deploy failure.
Change-Id: I9ec1dbb00d997ab6cb021bf0b698f7aae740e95d
