Save driver to container and skip incompat containers

For people who toggle drivers we want to save the driver used
to create a container so that if the driver changes we can skip
loading the container and it should not show up in docker ps

container.go

@@ -47,6 +47,7 @@ type Container struct {
 	HostnamePath   string
 	HostsPath      string
 	Name           string
+	Driver         string
 
 	cmd       *exec.Cmd
 	stdout    *utils.WriteBroadcaster

runtime.go

@@ -262,6 +262,7 @@ func (runtime *Runtime) restore() error {
 		return err
 	}
 	containers := make(map[string]*Container)
+	currentDriver := runtime.driver.String()
 
 	for i, v := range dir {
 		id := v.Name()
@@ -273,8 +274,14 @@ func (runtime *Runtime) restore() error {
 			utils.Errorf("Failed to load container %v: %v", id, err)
 			continue
 		}
-		utils.Debugf("Loaded container %v", container.ID)
-		containers[container.ID] = container
+
+		// Ignore the container if it does not support the current driver being used by the graph
+		if container.Driver == "" && currentDriver == "aufs" || container.Driver == currentDriver {
+			utils.Debugf("Loaded container %v", container.ID)
+			containers[container.ID] = container
+		} else {
+			utils.Debugf("Cannot load container %s because it was created with another graph driver.", container.ID)
+		}
 	}
 
 	register := func(container *Container) {
@@ -445,6 +452,7 @@ func (runtime *Runtime) Create(config *Config, name string) (*Container, []strin
 		// FIXME: do we need to store this in the container?
 		SysInitPath: sysInitPath,
 		Name:        name,
+		Driver:      runtime.driver.String(),
 	}
 	container.root = runtime.containerRoot(container.ID)
 	// Step 1: create the container directory.