Bug 14113: Silence t/Dates.t warnings and cleanup output.

Bug 14113: Silence t/Dates.t warnings and cleanup output.

The expectation of a user not freaking out over 'Illegal date'
messages is not sensible. Catch the messages, give a nicer
message.

Also, compress the veritical spacing on the output.

TEST PLAN
---------
1) $ prove t/Dates.t
   -- notice Illegal date messages, and extra lines between
      some sectional messages.
2) Apply patch
3) $ prove t/Dates.t
   -- Notice how nice and clean it is?
      Try it with -v to see all the output, including the
      expected warning type messages.
4) run koha qa test tools.

Test Remarks : complies with test plan.
Signed-off-by: Indranil Das Gupta (L2C2 Technologies) <indradg@gmail.com>a
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>