Propose of update to be runnable on Samsung S4

Use the real path of the storage directory + resize the image after camera shot, because the image is too large to display in kivy
This import of PIL is necessary because the original image take by the phone's camera may be too big. PIL is used to divide by 4 the picture, and make it readable by Kivy. I had to do this on Samsung S4, with default picture size of the camera. Without that, the picture does not apprear in the widget.