Use bootstrap default padding for nav-tabs

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/gl_bootstrap.scss

@@ -114,8 +114,7 @@ $list-group-active-bg: $bg_style_color;
 
   li {
     > a {
-      padding: 8px 20px;
-      margin-right: 7px;
+      margin-right: 5px;
       line-height: 20px;
       border-color: #EEE;
       color: #888;