System specification

Initial README with system specification from the system design discussion, #4.
What are you referring to by the "same resizing logic"? You would provide one dimension, i.e. 80. Say if you had a 160x240 image originally it would first shrink the image along the smaller dimension retaining the aspect ratio so it would turn to an 80x120 image and then the longer dimension would be cropped equally from both sides by 20 giving you an 80x80 image.