added iris gesture

Gesture.md

@@ -11,6 +11,8 @@ There are three pre-defined methods:
   - "*blink `<left|right>` eye*"
   - "*mouth `<percentage>` open*"  
   - "*head `<up|down>`*"  
+- iris(): implements:
+  - "*iris looking at camera*"
 - body(): implements:
   - "*leaning `<left|right>`*"
   - "*raise `<left|right>` hand*"
@@ -22,7 +24,8 @@ Example output of `result.gesture`:
 ```js
 [
   {face: "0", gesture: "facing camera"}
-  {face: "0", gesture: "head down"}
+  {face: "0", gesture: "head up"}
+  {iris: "0", gesture: "looking at camera"}
   {body: "0", gesture: "i give up"}
   {body: "0", gesture: "leaning left"}
   {hand: "0", gesture: "thumb forward middlefinger up"}