Add a Status field on ImageRepository

When clients want to use internal ImageRepositories (an ImageRepository that is backed by an OpenShift registry that can be automatically created on demand when a user pushes or pulls to it) a client needs to be able to know what registry URL that is in order to push images.

This pull adds a Status struct to an ImageRepository (as defined upstream, a set of attributes that represent the current condition of a resource) that conveys the *real* DockerImageRepository name (vs the value set on creation or update by a consumer).  It is populated when Get/List is called and defaults to a value set by an ENV attribute (although discussion in https://github.com/GoogleCloudPlatform/kubernetes/issues/1319 is leaning towards a service with a known name and namespace).

When a client requests an ImageRepository, the "status.dockerImageRepository" will be set to "dockerImageRepository" or to the value of `<defaultRegistry>/<namespace>/<name>`.  A properly configured default registry would know how to lookup `<namespace>/<name>` when pulling the image.

@ncdc review
Replace `"library"` with dockerDefaultNamespace