ux(playlist): migrate playlists page to new styles

public/app/features/playlist/partials/playlists.html

-<navbar icon="fa fa-fw fa-list" title="New Playlist">
+<navbar icon="fa fa-fw fa-list" title="Playlists">
 </navbar>
 
 <div class="page-container">
-  <div class="page-wide">
-
+  <div class="page-header">
+    <h1>Saved playlists</h1>
     <a class="btn btn-success pull-right" href="playlists/create">
       <i class="fa fa-plus"></i>
       New Playlist
     </a>
-
-    <h1>Saved playlists</h1>
+  </div>
 
   <table class="filter-table" style="margin-top: 20px">
     <thead>
@@ -47,5 +46,4 @@
     </tr>
   </table>
 
-  </div>
 </div>