Missions > Workers : UI

[eric-basley]

Review the way to view / add / remove workers for a mission

add: propose to add all workers not already included in the mission
remove: we can only remove workers without pending events on the mission, best will be to be tag a worker has inactive to avoid to select it for events but keep historical integrity
view: show as box with name, nb days accounted, nb pending days ....

Multiselect2 should be replaced by a more specific widget ...