update assets from bootstrap@3.3.7

assets/less/bootstrap/mixins/alerts.less

@@ -1,13 +1,14 @@
 // Alerts
 
 .alert-variant(@background; @border; @text-color) {
+  color: @text-color;
   background-color: @background;
   border-color: @border;
-  color: @text-color;
 
   hr {
     border-top-color: darken(@border, 5%);
   }
+
   .alert-link {
     color: darken(@text-color, 10%);
   }