Add clearfix utility

app/assets/stylesheets/addons/_utilities.scss

@@ -0,0 +1,29 @@
+// Micro clearfix provides an easy way to contain floats without adding additional markup
+//
+// Example usage:
+//
+//    // Contain all floats within .wrapper
+//    .wrapper {
+//      @include clear;
+//      .content,
+//      .sidebar {
+//        float : left;
+//      }
+//    }
+
+@mixin clear {
+  &:before,
+  &:after {
+    content : "";
+    display : table;
+  }
+  &:after {
+    clear : both;
+  }
+  zoom : 1;
+}
+
+
+// Acknowledgements
+//
+// Micro clearfix: [Nicolas Gallagher](http://nicolasgallagher.com/micro-clearfix-hack/)