ENH: Smaller test dataset (320MB)

We'll see if Travis can actually run this. I have a bad feeling that, with all the additional tests that will be run, we will exceed the ~50-minute limit.
I broke a test before leaving work Friday that I won't be able to fix until
Monday. But I expect it should be good to go after that. If you could look
at the mxne and gammamap tests, that would be good, but not critical.