Improve and polish pycaffe

- fix input preprocessing configuration in picking up on #733
- ~~add console output with human-readable labels and a grayscale flag to classify.py courtesy of @petewarden's #735~~ to be continued...
- fix #525 by scaling data to [0, 255] according to `Net.raw_scale`, doing mean subtraction, and then input scaling
- make mean argument an array instead of a file path for flexibility
- update examples' outputs given correct preprocessing, always include caffe pythonpath, and reword classification + time on a gtx 770