Add invite responsible to form

It is added so that user can enter email ids of other users, who they want to invite to become booth responsible.

app/controllers/admin/booths_controller.rb

@@ -129,7 +129,8 @@ module Admin
 
     def booth_params
       params.require(:booth).permit(:title, :description, :reasoning, :state, :picture, :conference_id,
-                                    :created_at, :updated_at, :submitter_relationship, :website_url, responsible_ids: [])
+                                    :created_at, :updated_at, :submitter_relationship, :website_url, :invite_responsible,
+                                    responsible_ids: [])
     end
   end
 end