Add test for #2037 failure mode
Get `Longitude` sign to come out right from `wrap_angle` when 0

Closes #2037
Fix test that incorrectly had '-0h00m00s 0d00m00s' and similar
Add test for correct behavior with dtypes
Use wrapping expression suggested by @mhvk
Merge pull request #2037 from eteq/fix-2037

Fix for ICRS coordinate giving RA -0 when input is 0