allow method chaining setup()

`setup()` returns `this`, which allows for an easier transition from old code:

```
var board = new arduino.Board(); // old
var board = new arduino.Board().setup(); // new
```

Author: tjanson

lib/board.js

@@ -77,6 +77,7 @@ Board.prototype.setup = function() {
       }
     }
   });
+  return this;
 }
 
 /*
@@ -238,8 +239,8 @@ Board.prototype.analogRead = function (pin) {
  * Utility function to pause for a given time
  */
 Board.prototype.delay = function (ms) {
-  ms += +new Date();
-  while (+new Date() < ms) { }
+  ms += Date.now();
+  while (Date.now() < ms) { }
 }
 
 /*