Reimplement timeline player
Change view when context is not editable

* Needed to change ability and remove current_tenant. This is temporary
and will be reverted soon.
* The api now sends an editable attribute used to define if the current user
is allowed to modify the context.
* If he is not, we replace forms by simple display of attributes.
* Also add a "new" state to create new context when a default instance is defined.