Add IsRunning to server interface

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Upstream-commit: 47edf3e8bf759270c243711eaed1faa1d4d61f35
Component: engine

components/engine/runtime/server.go

@@ -6,4 +6,5 @@ import (
 
 type Server interface {
 	LogEvent(action, id, from string) *utils.JSONMessage
+	IsRunning() bool // returns true if the server is currently in operation
 }