Spec: https://doc.ez.no/display/PR/Content+Tree

Big steps:

1. button action view which can expand itself (will be useful for others widget like Notification, Create, Search, ...)
2. the tree itself, no configuration as a first steps
[3. configuration overlay + tree update]

Questions/Problems/Remark:

• theme, dark background is not really nice
• performances
• default opening location if not on home
• should work for others part like Media