Add 'status' to state.go

Forgot to do this in previous PR.

Signed-off-by: Doug Davis <dug@us.ibm.com>

Author: Doug Davis

specs-go/state.go

@@ -6,6 +6,8 @@ type State struct {
 	Version string `json:"version"`
 	// ID is the container ID
 	ID string `json:"id"`
+	// Status is the runtime state of the container.
+	Status string `json:"status"`
 	// Pid is the process id for the container's main process.
 	Pid int `json:"pid"`
 	// BundlePath is the path to the container's bundle directory.