TST: add MINC2 tests with data files

Use submodule to import data for MINC2 tests.
TST: set up installation of h5py

To run MINC2 tests.
Merge pull request #280 from matthew-brett/add-minc2-tests

MRG: add MINC2 images repo, run tests on images

Install h5py for full tests using MINC2.