Merge pull request #89 from Igosuki/fix/ms-user-select

Add ms prefix to user-select for IE11

lib/compass/css3/_user-interface.scss

@@ -12,7 +12,7 @@
 @mixin user-select($select) {
   $select: unquote($select);
   @include experimental(user-select, $select,
-    -moz, -webkit, not(-o), not(-ms), -khtml, official
+    -moz, -webkit, not(-o), -ms, -khtml, official
   );
 }