Only show "Manage group members" in project member list when user has access

app/views/projects/project_members/_group_members.html.haml

@@ -4,10 +4,11 @@
     group members
     %small
       (#{members.count})
+    - if can?(current_user, :admin_group_member, @group)
       .pull-right
         = link_to group_group_members_path(@group), class: 'btn' do
           = icon('pencil-square-o')
-        Edit group members
+          Manage group members
   %ul.content-list
     - members.each do |member|
       = render 'groups/group_members/group_member', member: member, show_controls: false