Update documentation and add examples in JSDoc.

- Update Gruntfile.js
- Update ui.js and mobile.js files.
- Update documentation and add examples in JSDoc on:
 - ch.Collapsible.js
 - ch.Content.js
 - ch.Expandable.js
 - ch.Positioner.js
 - ch.Viewport.js
 - ch.Widget.js
 - ch.helpers.js
 - ch.util.js
 - ch.shortcuts.js