MER: Add packaging.
Add displayMarginBeginning/End to ListView and GridView.

This allows displaying content outside the visible area of
the view.

[ChangeLog][QtQuick] Add displayMarginBeginning/End to
ListView and GridView.

Change-Id: Idf9b5a0cd34a781c9603a9ad98ea189754972ba1
Reviewed-by: Alan Alpert (Personal) <416365416c@gmail.com>
MER: Remove property versioning from displayMarginBeginning/End.

These properties were upstreamed for Qt Quick 2.3. Allow them to be
used without "import QtQuick 2.3" here, to preserve previous behavior,
and avoid a partial 2.3 environment.

This hack can go away once jolla-store has been updated, which will be possible
sometime after the 5.2 upgrade.