Add a python data module.
Add a python data module.

For now, contains a function to convert from AFQ mat file to nodes.csv.

For an example input file: https://github.com/yeatmanlab/AFQ/blob/master/data/afq.mat

richford/AFQ-Browser,yeatmanlab/AFQ-Browser,arokem/AFQ-Browser,yeatmanlab/AFQ-Browser,richford/AFQ-Browser,richford/AFQ-viz,arokem/AFQ-Browser,yeatmanlab/AFQ-Browser,yeatmanlab/AFQ-viz,richford/AFQ-Browser,arokem/AFQ-Browser,richford/AFQ-viz,yeatmanlab/AFQ-viz