Remove mxDateTime test of local representation

[taldcroft]

From @mbaski and sot/skare#18:

The Chandra.Time test ran fine on Windows (though I had to run it the way I normally do, through the setup.py utility due to stdin issues) - just the one difference in date representation that always occurs:

AssertionError: '01/01/99 12:13:14' != 'Fri Jan 1 12:13:14 1999'

This test isn't important, just cut it so the Windows tests pass.