Make it a module + add data_dict creation

Adds a .gitignore file
and __init__.py, which allows a directory to be loaded as a package

If you move the pymvpa_rs directory to your python's site-packages folder, you can then call 
import pymvpa_rs
in python. I have it loading in everything from wrapit_pymvpa, which also loads in everything from pymvpa and all the other import statements from wrapit. Not sure what the best way to handle all of the imports is. Kinda messy as is.

I also added a function to wrapit that loads separate subject files in (with the option to also load in the Sample Attributes, remove invariant features, or mask the data), and then return the data_dict (optionally saving the dict as an hdf5 file).