Imports of package trustpinning

PathSynopsis
crypto/x509Package x509 implements a subset of the X.509 standard.
errorsPackage errors implements functions to manipulate errors.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/sirupsen/logrusPackage logrus is a structured logger for Go, completely API compatible with the standard library logger.
github.com/theupdateframework/notary/tuf/data
github.com/theupdateframework/notary/tuf/signed
github.com/theupdateframework/notary/tuf/utilsPackage utils contains tuf related utility functions however this file is hard forked from https://github.com/youmark/pkcs8 package.
stringsPackage strings implements simple functions to manipulate UTF-8 encoded strings.