Config page

New files: options.html and options.js. This files are the used by the default page in the configuration of plugin. The html file describes the view. And javascript file saves and restore the data storage.

In manifest: options_ui defines the html page of configuration. Added "storage" in "permission".

Refactoring index.js: The methode "then" of instance Promise is asynchronus. Modification: the main loop becomes a function. The methode then call ConfigColor. In failed to get color from storage the default color are text in red and background in yellow.