Fix Option Overrides

Problem: The user is currently presented with a vague dialog whenever a theme wants to override options. If they click yes, the theme can override whatever it wants, and if they click no then it can't even change the width or height of the screenlet. This is problematic from both a usability and securtiy standpoint.

Solution:
- Remove the dialog asking user if they want to allow the theme to override options.
- Add a parameter to Option's constructor allowing developers to specify whether the option may be overriden by a theme or not.

Migration: Allow overrides for all options until we can update the Screenlet class and all of the necessary applets. (This is pretty much what we're doing now anyway.)