Image Recognition - Find the largest face

[wrussell1999]

To prevent dodgy crops, pick the largest face in the array and use that. Using the Google Cloud Vision API

[wei]

This snippet below is currently always picking the last face in the faces array:

class-photo/class_photo/face.py

Lines 46 to 47 in e281b74

	for face in faces:
	box = [(vertex.x, vertex.y) for vertex in face.bounding_poly.vertices]

We should add a conditional here to only set the box variable if the new face width/height is larger than the one stored in box. or just do a sort by width/height and take the largest one.