style Sign In button with jQuery

IPython/frontend/html/notebook/static/js/loginmain.js

@@ -20,6 +20,7 @@ $(document).ready(function () {
 
     $('div#left_panel').addClass('box-flex');
     $('div#right_panel').addClass('box-flex');
+    $('input#signin').button();
 
     // These have display: none in the css file and are made visible here to prevent FLOUC.
     $('div#header').css('display','block');

IPython/frontend/html/notebook/templates/login.html

@@ -31,7 +31,7 @@
     <div id="content_panel">
         <form action="/login?next={{url_escape(next)}}" method="post">
             Password: <input type="password" name="password">
-            <input type="submit" value="Sign in">
+            <input type="submit" value="Sign in" id="signin">
         </form>
     </div>
     <div id="right_panel">