Consistent directory for vgg-19 and train2014 data

[mapmeld]

Hi - I'm getting started using FloydHub with this project, and this inconsistency with paths in setup.sh and style.py made it difficult for me to figure out where to download the training data. If the absolute path /input or /output are meant to be used on FloydHub's machines, then this PR is incorrect, but there still should be only one used, and some info on what to do locally.

Thanks!