Add images & image repositories

Add initial support for images & image repositories.

Add registry webhook to support adding images and tags
to image repositories when a registry's image repository
is updated.
Merge pull request #45 from ncdc/images

Merged by openshift-bot
Disable coverage for Travis + go tip
Merge pull request #64 from ncdc/disable-coverage-travis-go-tip

Disable coverage for Travis + go tip