Imports of gorename command

PathSynopsis
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
go/buildPackage build gathers information about Go packages.
golang.org/x/tools/go/buildutilPackage buildutil provides utilities related to the go/build package in the standard library.
golang.org/x/tools/refactor/renamePackage rename contains the obsolete implementation of the deleted golang.org/x/tools/cmd/gorename.
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.