ImageStreamTag definitions must use from element to ensure the tag is imported

Currently, we do not define any repository information for image stream tag definitions and rely on the import mechanism discovering the tags through the dockerImageRepository field. The problem is that this is not guaranteed to import any of the tags listed in the image stream, which could have the effect of breaking the templates (because the tag does not exist within OpenShift).

The solution is to define a from element on each tag for each image stream, e.g. https://github.com/openshift/origin/blob/master/examples/image-streams/image-streams-rhel7.json#L43-L46. Note, for our images, we will also need to specify the tag, as the default is "latest."

We should also remove the dockerImageRepository field from the image streams as the tags that will be imported will be random, i.e. nondeterministic.