Code review comment for lp:~rpadovani/ubuntu-calendar-app/1231136

I implemented it, but due to bug #1231558 we have to pass args before command:
qmlscene calendar:///?starttime=1234567889 /usr/share/calendar-app/calendar.qml

I implemented starttime and endtime with value as number of seconds since UNIX epoch in the UTC timezone.

https://bugs.launchpad.net/ubuntu-ui-toolkit/+bug/1231558