This is necessary for this test to pass on Windows, because otherwise a handle to test.fits is kept open by the mmap.  I suppose this could also use memmap=False.  I thought I had included this commit before I merged the original PR for #507 but apparently I did not.
Merge pull request #930 from iguananaut/issue-507

Followup to #507
Merge pull request #927 from mdboom/vo/table_read_unnamed_tables

Make Table.read find VO tables with no names
Fix #928 -- a votable without a mask can not be created