Adds a test that would have caught and a fix for a slight bug in FitsHDU.fromfile.  I think this was always supposed to say HDUList.fromfile.  I don't think this interface is often used though which is why it was not caught before now.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2308 ed100bfc-0583-0410-97f2-c26b58777a21