Hard-coded paths in bidsInitVista.m

bidsInitVista.m contains hard-coded paths for '/Volumes/server/Projects/Anatomy' -- this is fine as long as we run in the Winawerlab and use /Volumes/server as the mount-point for acadia, but this caused some confusion when trying to run the code on the NYU HPC. I'd suggest that there be a more informative error message and an environment override for directory (I'll work on a pull request).