Bug 19816: Regression tests

Bug 19816: Regression tests

This patch adds tests for the rfc3339 behaviour when dateonly => 1.

To test:
- Run:
  $ kshell
 k$ prove t/DateUtils.t
=> SUCCESS: Tests pass
- Apply this patch
- Run:
 k$ prove t/DateUtils.t
=> FAIL: dateonly is not implemented

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 7e69ab62a5ef3fbd350c6606d25b5ab6f6bc168e)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>