(ui) fix menu width on small size screens, closes https://github.com/opnsense/core/issues/657

src/opnsense/mvc/app/views/layout_partials/base_menu_system.volt

-<aside id="navigation" class="page-side col-xs-12 col-sm-2 hidden-xs">
+<aside id="navigation" class="page-side col-xs-12 col-sm-3 col-lg-2 hidden-xs">
     <div class="row">
         <nav class="page-side-nav" role="navigation">
             <div id="mainmenu" class="panel" style="border:0px" >

src/opnsense/mvc/app/views/layouts/default.volt

@@ -198,7 +198,7 @@
     </nav>
   </header>
 
-  <main class="page-content col-sm-10 col-sm-push-2 ">
+  <main class="page-content col-sm-9 col-sm-push-3 col-lg-10 col-lg-push-2">
 
     <!-- menu system -->
     {{ partial("layout_partials/base_menu_system") }}

src/www/fbegin.inc

@@ -107,8 +107,8 @@ if($need_alert_display == true) {
   </nav>
 </header>
 
-<main class="page-content col-sm-10 col-sm-push-2">
-    <aside id="navigation" class="page-side col-xs-12 col-sm-2 hidden-xs">
+<main class="page-content col-sm-9 col-sm-push-3 col-lg-10 col-lg-push-2">
+    <aside id="navigation" class="page-side col-xs-12 col-sm-3 col-lg-2 hidden-xs">
         <div class="row">
             <nav class="page-side-nav" role="navigation">
                 <div id="mainmenu" class="panel" style="border:0px" >