Deserialize the time into UTC instead of local time
Ensure the execution finishes before proceeding to other test

Fixes random issues with TestExecutionLog
Do not use simple world for testing

The simple world tries to resume planned plans when creating new
world. In tests, it introduces some undeterminism and causes tests to
fail at some seeds.
Merge pull request #126 from iNecas/fix-timezones

Deserialize the time into UTC instead of local time