Removes 3 methods from the builder.Backend interface
Remove the coupling between imageContexts, imageMounts and the builder.
Signed-off-by: Daniel Nephin <dnephin@docker.com>
Remove forked reference package. Use normalized named values
everywhere and familiar functions to convert back to familiar
strings for UX and storage compatibility.
Enforce that the source repository in the distribution metadata
is always a normalized string, ignore invalid values which are not.
Update distribution tests to use normalized values.
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
