Add basic stats

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

stats.go

@@ -0,0 +1,15 @@
+package containerd
+
+import "github.com/rcrowley/go-metrics"
+
+var (
+	ContainerStartTimer = metrics.NewTimer()
+	ContainersCounter   = metrics.NewCounter()
+)
+
+func Metrics() map[string]interface{} {
+	return map[string]interface{}{
+		"container-start-time": ContainerStartTimer,
+		"containers":           ContainersCounter,
+	}
+}