suggestion for transforms.Scale()

[yanghuanflc]

I suggest to modified transforms.Scale() to accept two type of size input:
1, If isinstance(self.size, int), resize the image short side to self.size
2. Else, resize the image each side according to self.size

The code looks like this:

class Scale(object):
    def __init__(self, size, interpolation=Image.BILINEAR):
        self.size = size
        self.interpolation = interpolation

    def __call__(self, img):
        if isinstance(self.size, int):
            w, h = img.size
            if (w <= h and w == self.size) or (h <= w and h == self.size):
                return img
            if w < h:
                ow = self.size
                oh = int(self.size * h / w)
                return img.resize((ow, oh), self.interpolation)
            else:
                oh = self.size
                ow = int(self.size * w / h)
                return img.resize((ow, oh), self.interpolation)
        else:
            return img.resize(self.size, self.interpolation)

[soumith]

Seems like a reasonable solution. Can you send a PR to do this? Thanks.

[yanghuanflc]

PR #133