Fix timezone related sameday filter test failure

In certain timezones, 201304151312 UTC is not actually the same day
as 201304152219 any 201304151756. This was causing the test for the
'sameday' filter operator to fail. (I'm in GMT+10).

This is a quick-fix. I've just adjusted the timestamps to be close
together so they will be same day no matter what timezone you're in.