Left align "File" instead of menu edge.

IPython/html/static/notebook/less/menubar.less

@@ -1,54 +1,56 b''
 #menubar {
   margin-bottom: 15px;
   margin-top: 2px;
+  margin-left: -32px;
+  margin-right: -32px;
 }
 
 #menubar .navbar-inner {
   min-height: 28px;
   border-top: 1px;
   border-radius: 0px 0px @border-radius-base @border-radius-base;
 }
 
 #menubar .navbar {
   margin-bottom: 8px;
 }
 
 .nav-wrapper {
   border-bottom: 1px solid @navbar-default-border;
 }
 
 #menubar li.dropdown {
   line-height: 12px;
 }
 
 #menubar .navbar-right {
   // Add some padding to the right aligned items.
   padding-top: 5px;
 }
 
 
 i.menu-icon {
   // add padding to account for float-right
   padding-top: 4px;
 }
 
 ul#help_menu li a{
     overflow: hidden;
     padding-right: 2.2em;
     i {
         margin-right: -1.2em;
     }
 }
 
 ul#menus {
   float: left;
 }
 
 // Make sub menus work in BS3.
 // Credit: http://www.bootply.com/86684
 .dropdown-submenu{position:relative;}
 .dropdown-submenu>.dropdown-menu{top:0;left:100%;margin-top:-6px;margin-left:-1px;-webkit-border-radius:0 6px 6px 6px;-moz-border-radius:0 6px 6px 6px;border-radius:0 6px 6px 6px;}
 .dropdown-submenu:hover>.dropdown-menu{display:block;}
 .dropdown-submenu>a:after{display:block;content:" ";float:right;width:0;height:0;border-color:transparent;border-style:solid;border-width:5px 0 5px 5px;border-left-color:#cccccc;margin-top:5px;margin-right:-10px;}
 .dropdown-submenu:hover>a:after{border-left-color:#ffffff;}
 .dropdown-submenu.pull-left{float:none;}.dropdown-submenu.pull-left>.dropdown-menu{left:-100%;margin-left:10px;-webkit-border-radius:6px 0 6px 6px;-moz-border-radius:6px 0 6px 6px;border-radius:6px 0 6px 6px;}