Fix search input text selection in Firefox 17 and older

Fixes #57.

assets/stylesheets/global/_classes.scss

@@ -9,7 +9,7 @@
 
 %user-select-none {
   -webkit-user-select: none;
-     -moz-user-select: none;
+     -moz-user-select: -moz-none;
       -ms-user-select: none;
           user-select: none;
 }