Log Message:
Updated p5-DateTime to 1.2800.

1.28   2016-05-21

- Fixed handling of some floating point epochs. Because DateTime treated the
  epoch like a string instead of a number, certain epochs with a non-integer
  value ended up treated like integers (Perl is weird). Patch by Christian
  Hansen. GitHub #15. This also addresses the problem that GitHub #6 brought
  up.