Imports of securitypolicy command

PathSynopsis
encoding/base64Package base64 implements base64 encoding as specified by RFC 4648.
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/BurntSushi/tomlPackage toml implements decoding and encoding of TOML files.
github.com/Microsoft/hcsshim/internal/tools/securitypolicy/helpers
github.com/Microsoft/hcsshim/pkg/securitypolicy
osPackage os provides a platform-independent interface to operating system functionality.