Change jsonmodels example to use open source controls by default.

Also worked around the issues with gauge style backgrounds in
the enterprise controls version and tweaked the default ui
a bit.

Change-Id: Ia0887373ad4a0f45f20f759daeedc7abc433cca5
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>