Allow us to tell the difference between the following cases:

1. Just resize the image to width 50 (preserving aspect ratio)

    image.jpg?w=50

2. No resizing just adjust the quality to 50%:

    image.jpg?q=50

Prior to this change those would both be stored as:

    giraffe/image_50.jpg

Now they'll be stored as:

    giraffe/image_q50.jpg
    giraffe/image_w50.jpg
Worked with Jake to make our resizing work much more nicely:
 - we now resize and crop to fit
 - you can specify just width or height and the aspect ratio will be preserved