Also fix timezone related eachday test failure

In some timezones, (eg GMT+6) the modified timestamps for the
'TiddlerOne' and 'Tiddler Three' test tiddlers were actually on
the same day. This was causing the 'eachday' filter test to fail.

Similar to the fix in commit 8487221, this just adjusts the
timestamp to ensure the test passes in any timezone.
Merge pull request #388 from simonbaird/sameday_tz_fix

Also fix timezone related eachday test failure