Uses the magic of numpy.genfromtxt to make sdss.crossID return a record array, simplifying the code at the same time.
The get_* helpers should work as before.
Make sure than numpy.genfromtxt returns at least a 1D array.
This is to satisfy the current syntax of the get_* helper functions,
as well as to make the tests pass.
Merge pull request #98 from jwoillez/sdss_record_array_rebased

SDSS upgrade to numpy's record arrays.