Imports of docker-device-tool command

PathSynopsis
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/dotcloud/docker/graphdriver/devmapper
osPackage os provides a platform-independent interface to operating system functionality.
pathPackage path implements utility routines for manipulating slash-separated paths.
sortPackage sort provides primitives for sorting slices and user-defined collections.
strconvPackage strconv implements conversions to and from string representations of basic data types.
stringsPackage strings implements simple functions to manipulate UTF-8 encoded strings.