Imports of package cache

PathSynopsis
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/docker/distribution/contextPackage context provides several utilities for working with Go's context in http requests.
github.com/docker/distribution/digest
github.com/garyburd/redigo/redisPackage redis is a client for the Redis database.
golang.org/x/net/contextPackage context has been superseded by the standard library context package.