Imports of ctr command

PathSynopsis
cryptoPackage crypto collects common cryptographic constants.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/containerd/containerd/cmd/ctr/app
github.com/containerd/containerd/pkg/hasher
github.com/containerd/containerd/pkg/seedPackage seed provides an initializer for the global math/rand seed.
github.com/urfave/cliPackage cli provides a minimal framework for creating and organizing command line Go applications.
osPackage os provides a platform-independent interface to operating system functionality.