updated UI, default profile name, check for existing supervised user before create

chrome/browser/resources/md_user_manager/user_manager_styles.html

 <link rel="import" href="chrome://md-user-manager/shared_styles.html">
 
 <dom-module id="user-manager-styles">
   <template>
     <style include="shared-styles">
       body {
         background-color: #eee;
       }
 
       /* Overrides for the desktop user manager screen. */
+      #login-header-bar {
+        bottom: 0;
+        left: 0;
+        position: absolute;
+        right: 0;
+      }
 
       #outer-container {
         min-height: 0;
       }
 
       .bubble.faded {
         opacity: 0;
       }
 
       .pod {
@@ skipping 181 matching lines @@
 
       .action-box-remove-user-warning .remove-warning-button:focus {
         /* Override the default blue border inherited from
         button.custom-appearance:focus. */
         border: 1px solid transparent !important;
         box-shadow: inset 0 0 0 1px #fff;
       }
     </style>
   </template>
 </dom-module>