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/internal/schema2/pause_notification.go

@@ -11,6 +11,5 @@ package hcsschema
 
 //  Notification data that is indicated to components running in the Virtual Machine.
 type PauseNotification struct {
-
 	Reason string `json:"Reason,omitempty"`
 }