GPII-566: Revived the contrastEnabled adjuster.
Removed the "default" contrast theme selection.
When contrast is disabled, set default theme programmatically.
Contrast theme panel is conditional to contrastEnabled.
GPII-523: Added model transformation for contrastEnabled.
Merge pull request #21 from chrispetsos/GPII-566

GPII-566: Revived the contrastEnabled adjuster. - merging after review from Justin