Rudder

In the rule configuration, we have a nice zone right of the group tree that lists applied groups and allows to remove them, plus a nice group mouseover that makes clear how to applied/remove a group to that group.

We want to 1/ make the user better get in a glimpse applied directive, 2/ make more obvious how to add/remove directives to a rule, and 3/make the interface more consistant by replicating the group's zone and mouseover behavior for directives.