feat(gridster): Common.js support

Closes ducksboard#434

Author: joaoafrmartins

src/jquery.collision.js

@@ -7,8 +7,9 @@
  */
 
 ;(function(root, factory) {
-
-    if (typeof define === 'function' && define.amd) {
+    if (typeof exports === 'object') {
+        module.exports = factory(require('jquery'), require('./jquery.coords.js'));
+    } else if (typeof define === 'function' && define.amd) {
         define('gridster-collision', ['jquery', 'gridster-coords'], factory);
     } else {
         root.GridsterCollision = factory(root.$ || root.jQuery,

src/jquery.coords.js

@@ -7,11 +7,12 @@
  */
 
 ;(function(root, factory) {
-
-    if (typeof define === 'function' && define.amd) {
+    if (typeof exports === 'object') {
+        module.exports = factory(require('jquery'));
+    } else if (typeof define === 'function' && define.amd) {
         define('gridster-coords', ['jquery'], factory);
     } else {
-       root.GridsterCoords = factory(root.$ || root.jQuery);
+        root.GridsterCoords = factory(root.$ || root.jQuery);
     }
 
 }(this, function($) {

src/jquery.draggable.js

@@ -7,8 +7,9 @@
  */
 
 ;(function(root, factory) {
-
-    if (typeof define === 'function' && define.amd) {
+    if (typeof exports === 'object') {
+        module.exports = factory(require('jquery'));
+    } else if (typeof define === 'function' && define.amd) {
         define('gridster-draggable', ['jquery'], factory);
     } else {
         root.GridsterDraggable = factory(root.$ || root.jQuery);

src/jquery.gridster.extras.js

@@ -1,6 +1,7 @@
 ;(function(root, factory) {
-
-    if (typeof define === 'function' && define.amd) {
+    if (typeof exports === 'object') {
+        module.exports = factory(require('jquery'), require('./jquery.gridster.js'));
+    } else if (typeof define === 'function' && define.amd) {
         define(['jquery', 'gridster'], factory);
     } else {
         root.Gridster = factory(root.$ || root.jQuery, root.Gridster);

src/jquery.gridster.js

@@ -7,8 +7,11 @@
  */
 
 ;(function(root, factory) {
-
-    if (typeof define === 'function' && define.amd) {
+    if (typeof exports === 'object') {
+        module.exports = factory(require('jquery'),
+            require('./jquery.draggable.js'), require('./jquery.collision.js'),
+            require('./utils.js'));
+    } else if (typeof define === 'function' && define.amd) {
         define(['jquery', 'gridster-draggable', 'gridster-collision'], factory);
     } else {
         root.Gridster = factory(root.$ || root.jQuery, root.GridsterDraggable,