Add Exec IDs

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

windows/hcs/process.go

@@ -14,6 +14,7 @@ import (
 type Process struct {
 	hcsshim.Process
 
+	id       string
 	pid      uint32
 	io       *IO
 	ec       uint32
@@ -22,6 +23,10 @@ type Process struct {
 	ecSync   chan struct{}
 }
 
+func (p *Process) ID() string {
+	return p.id
+}
+
 func (p *Process) Pid() uint32 {
 	return p.pid
 }