Show add button just for agents.

app/assets/javascripts/app/controllers/ticket_overview.coffee

@@ -128,6 +128,7 @@ class Navbar extends App.Controller
     items = App.OverviewIndexCollection.get()
     @html App.view("agent_ticket_view/navbar#{ if @vertical then '_vertical' }")
       items: items
+      isAgent: @isRole('Agent')
 
     while @clone.width() > @tabsHolder.width()
       @tabClone.not('.hide').last().addClass('hide')

app/assets/javascripts/app/views/agent_ticket_view/navbar_vertical.jst.eco

@@ -21,9 +21,11 @@
     <% end %>
   </div>
 </div>
+<% if @isAgent: %>
 <a class="btn btn--success btn--quad" href="#ticket/create">
   <%- @Icon('plus') %>
 </a>
+<% end %>
 <% if @items: %>
 <div class="tabs tabs--inline tabs--big tabs-clone u-invisible js-tabsClone">
   <% for item in @items: %>