Use of LocalStorage

[mathieuLivebardon]

Following this #785 (comment).

We are using LocalStorage in some of our packages to save information and reuse it even after a web page reload. However, documentation is lacking to understand how to handle it well.

• Provide a documentation of how using localStorage in web application
• When using it gives the possibility of users (examples) or developers (packages) to disable it or clear it
  • I also think we shouldn't use 'window.beforeunload' event to write on localStorage because he avoids us to use the browser console to clear localStorage (localStorage.clear());