(feat) barebones routing setup

Using a super super simple regex, I'm able to pull out strings
from the path:

 - format: either jpg or png
 - width: number between 0 and 9999
 - height: number between 0 and 9999

The url looks like this: /format/width/height/. Ex:

 /jpg/400/300/

Note that I'm not actually using those strings in anyway yet, so
the image created on disk continues to be the same dimensions as
the source image on the remote server.