Added ColorPalette, basic colorSelector and tests for palette.

Displays color palette in div container. Allows user to click and select
color from palette or from the html5 input color selector. Color
selector box is updated with the current selected color.
colorpalette_test.js only tests color palette.

R=calamity@chromium.org, jackhou@chromium.org

Review URL: https://codereview.appspot.com/46420043