Imports of package builder

PathSynopsis
github.com/docker/docker/api/types
github.com/docker/docker/api/types/backendPackage backend includes types to send information to server backends.
github.com/docker/docker/api/types/container
github.com/docker/docker/container
github.com/docker/docker/layerPackage layer is package for managing read-only and read-write mounts on the union file system driver.
github.com/docker/docker/pkg/containerfs
golang.org/x/net/contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
ioPackage io provides basic interfaces to I/O primitives.