add utilities.less file for generic classes

lib/bootstrap.less

@@ -52,5 +52,8 @@
 @import "labels.less";
 @import "progress-bars.less";
 
+// Utility classes
+@import "utilities.less"; // Has to be last to override when necessary
+
 // Responsive
 @import "responsive.less";

lib/scaffolding.less

@@ -70,22 +70,6 @@ a {
   }
 }
 
-// Quick floats
-.pull-right {
-  float: right;
-}
-.pull-left {
-  float: left;
-}
-
-// Toggling content
-.hide {
-  display: none;
-}
-.show {
-  display: block;
-}
-
 
 // GRID SYSTEM
 // -----------

lib/utilities.less

@@ -0,0 +1,23 @@
+// UTILITY CLASSES
+// ---------------
+
+// Quick floats
+.pull-right {
+  float: right;
+}
+.pull-left {
+  float: left;
+}
+
+// Toggling content
+.hide {
+  display: none;
+}
+.show {
+  display: block;
+}
+
+// Visibility
+.invisible {
+  visibility: hidden;
+}