Yún REST Driver

* Yún REST Driver
```
>>> import pingo
>>> y = pingo.arduino.ArduinoYun('127.0.0.1:5000')
>>> p = y.pins['A0']
```
* yunserver.py: Based on http://arduino.cc/en/Tutorial/Bridge. It helps on testing
```
(env)vido@magrela:~/documents/pingo/scripts$ ./yunserver.py 
 * Running on http://127.0.0.1:5000/
 * Restarting with reloader
127.0.0.1 - - [05/Dec/2014 08:59:16] "GET /arduino/mode/13/output HTTP/1.0" 200 -
```