Use a JQuery-based color picker for the Flamingo Theme Application

As explained in XWIKI-11100, the Flamingo Theme Application is using "procolor", which is a color picker written in Prototype. It causes some problems since the rest of the application is written with jQuery.

Moreover, there is a bug (XWIKI-11100). It is better to replace the current color picker by an other that uses jQuery than fixing the bug with the already deprecated procolor.

It should also fix the fact that when the color picker is used, the preview frame is not refreshed even if the "auto refresh" checkbox is enabled.