Remove encryption code from containerd core

We are separating out the encryption code and have designed a few new
interfaces and APIs for processing content streams.  This keep the core
clean of encryption code but enables not only encryption but support of
multiple content types ( custom media types ).

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

vendor/golang.org/x/crypto/openpgp/canonical_text.go

@@ -1,59 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package openpgp
-
-import "hash"
-
-// NewCanonicalTextHash reformats text written to it into the canonical
-// form and then applies the hash h.  See RFC 4880, section 5.2.1.
-func NewCanonicalTextHash(h hash.Hash) hash.Hash {
-	return &canonicalTextHash{h, 0}
-}
-
-type canonicalTextHash struct {
-	h hash.Hash
-	s int
-}
-
-var newline = []byte{'\r', '\n'}
-
-func (cth *canonicalTextHash) Write(buf []byte) (int, error) {
-	start := 0
-
-	for i, c := range buf {
-		switch cth.s {
-		case 0:
-			if c == '\r' {
-				cth.s = 1
-			} else if c == '\n' {
-				cth.h.Write(buf[start:i])
-				cth.h.Write(newline)
-				start = i + 1
-			}
-		case 1:
-			cth.s = 0
-		}
-	}
-
-	cth.h.Write(buf[start:])
-	return len(buf), nil
-}
-
-func (cth *canonicalTextHash) Sum(in []byte) []byte {
-	return cth.h.Sum(in)
-}
-
-func (cth *canonicalTextHash) Reset() {
-	cth.h.Reset()
-	cth.s = 0
-}
-
-func (cth *canonicalTextHash) Size() int {
-	return cth.h.Size()
-}
-
-func (cth *canonicalTextHash) BlockSize() int {
-	return cth.h.BlockSize()
-}