Following on from #2849, it became apparent to me that astropy.utils.misc was getting a bit cluttered, so this introduces a few new astropy.utils modules so that astropy.utils.misc could be broken up a bit.
Add a test from pyfits that was never copied over for some reason (https://github.com/spacetelescope/PyFITS/blob/master/lib/pyfits/tests/test_core.py#L718)
Remove Csv comment character to fix regression from #2812
Merge pull request #2860 from taldcroft/csv-regression-2812

Change Csv comment character to None to fix regression from #2812
Merge pull request #2858 from embray/fits/missing-test

Add missing test from PyFITS
Added a changelog entry
Merge pull request #2857 from embray/utils/reorg

Reorganize astropy.utils.misc a bit