Provide fodder for run_task integration testing.
Add integration tests for task running

This makes it much simpler to detect how runner will behave on various platforms,
for instance, these tests would reveal problems with using runner on windows
via cmd.exe.
Cleanup un-necessary global and decrease possible wait time on 'sleep' task (in case max_time fails)
Merge pull request #8 from mrrrgn/tests

Tests