Add Driver channel for events

driver.go

@@ -7,6 +7,7 @@ type Driver struct {
   Pin string
   Name string
   Params map[string]string
+  Events map[string]chan interface{}
 }
 
 func NewDriver(d Driver) Driver {

gobot.go

@@ -26,4 +26,11 @@ func After(t string, f func()) {
 func Random(min int, max int) int {
   rand.Seed(time.Now().UTC().UnixNano())
   return rand.Intn(max - min) + min
-}
+}
+
+func On(cs chan interface{}) interface{}{
+  for s := range cs {
+    return s
+  }
+  return nil
+}