add learn face service

Add services to learn face and forget person.
http://doc.aldebaran.com/2-1/naoqi/peopleperception/alfacedetection-api.html#ALFaceDetectionProxy::learnFace__ssCR
http://doc.aldebaran.com/2-1/naoqi/peopleperception/alfacedetection-api.html#ALFaceDetectionProxy::forgetPerson__ssCR