Imports of package builder

PathSynopsis
contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
github.com/docker/docker/api/types
github.com/docker/docker/api/types/backend
github.com/docker/docker/api/types/container
github.com/docker/docker/container
github.com/docker/docker/image
github.com/docker/docker/layer
github.com/docker/docker/pkg/containerfs
ioPackage io provides basic interfaces to I/O primitives.