[nemo-qml-plugin-calendar] Fix all-day status missing on created events

KCalCore/IncidenceBase::setDtStart() overwrites the all-day status.
Unclearif that's really the proper thing to do, so working around by
changing setter ordering.
Merge pull request #46 from pvuorela/master

[nemo-qml-plugin-calendar] Fix all-day status missing on created events