Make primaryColor transparent by default, and change it only when it is sent through props.

[KiranCNayak]

I am trying to take the backgroundColor and fix it as one of the colors to either primaryColor or secondaryColor. But there is no option to do that in the current setup as the default colors for primaryColor is #eeeee and for secondaryColor is #dddddd.

So it would be helpful if you could add support to have backgroundColor be primaryColor unless it is specified through props instead of setting it to #eeeeee.