Revendor github.com/Microsoft/hcsshim

1. Revendors github.com/Microsoft/hcsshim to the latest known good commit.
This includes numerous bug fixes and improvements.

2. Vendors indirect dependency on go.opencensus.io since hcsshim now uses trace
correlation.

Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>

vendor/github.com/Microsoft/hcsshim/layer.go

@@ -4,7 +4,7 @@ import (
 	"crypto/sha1"
 	"path/filepath"
 
-	"github.com/Microsoft/hcsshim/internal/guid"
+	"github.com/Microsoft/go-winio/pkg/guid"
 	"github.com/Microsoft/hcsshim/internal/wclayer"
 )
 
@@ -77,7 +77,7 @@ type GUID [16]byte
 
 func NameToGuid(name string) (id GUID, err error) {
 	g, err := wclayer.NameToGuid(name)
-	return GUID(g), err
+	return g.ToWindowsArray(), err
 }
 
 func NewGUID(source string) *GUID {
@@ -88,7 +88,7 @@ func NewGUID(source string) *GUID {
 }
 
 func (g *GUID) ToString() string {
-	return (guid.GUID)(*g).String()
+	return guid.FromWindowsArray(*g).String()
 }
 
 type LayerReader = wclayer.LayerReader