Use hsl colors for contracts
Letting admins pick rgb colors is sure to make an inconsistent mess. Instead put the saturation and brightness part of the colors in the settings document and let the admins pick the hue.
This would mean dropping the html5 color picker. Instead just use a simple slider. Something like the top slider here: http://hslpicker.com/ , but we don't need to be that fancy. Updating a preview color next to a standard html5 slider is sufficient.