Imports of package releaser

PathSynopsis
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/gohugoio/hugo/common/hugo
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.
os/execPackage exec runs external commands.
path/filepathPackage filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths.
regexpPackage regexp implements regular expression search.
stringsPackage strings implements simple functions to manipulate UTF-8 encoded strings.