Update gems, use d3 gem, initial bootstrap v3 port

app/views/layouts/_user_menu.html.haml

@@ -1,5 +1,3 @@
-%li.nav-header
-  = current_user.person.public_name if current_user.person
 %li
   = link_to(edit_user_registration_path) do
     %i.icon-wrench
@@ -15,7 +13,7 @@
     Sign out
 -if has_role?(current_user, "admin") || has_role?(current_user, "organizer")
   %li.divider
-  %li.nav-header
+  %li.dropdown-header
     Conferences
   - @conferences.each do |conference|
     %li
@@ -28,7 +26,7 @@
       %i.icon-plus
       New Conference
   %li.divider
-  %li.nav-header
+  %li.dropdown-header
     People
   %li
     = link_to(admin_users_path) do