Merge branch '17338-sidebar-width' into 'master'

Reduce width of side nav

Closes #17338    
Part of #14838    
Left: old; Right: new    
<img src="/uploads/7dba5f22d6bdf1249bab5166addb25b5/Screen_Shot_2016-05-10_at_4.34.07_PM.png" width="500px">

See merge request !4109

app/assets/stylesheets/framework/sidebar.scss

@@ -312,7 +312,7 @@
     }
 
     .nav-sidebar li a {
-      width: 230px;
+      width: $sidebar_width;
 
       &.back-link {
         i {

app/assets/stylesheets/framework/variables.scss

@@ -2,7 +2,7 @@
  * Layout
  */
 $sidebar_collapsed_width: 62px;
-$sidebar_width: 230px;
+$sidebar_width: 220px;
 $gutter_collapsed_width: 62px;
 $gutter_width: 290px;
 $gutter_inner_width: 258px;