fix handle option

Author: troolee

dist/gridstack.js

@@ -411,7 +411,7 @@
                 handles: 'se'
             }),
             draggable: _.defaults(opts.draggable || {}, {
-                handle: opts.handle_class || (opts.handle ? '.' + opts.handle : '') || '.grid-stack-item-content',
+                handle: (opts.handle_class ? '.' + opts.handle_class : (opts.handle ? opts.handle : '')) || '.grid-stack-item-content',
                 scroll: false,
                 appendTo: 'body'
             })
@@ -517,7 +517,7 @@
         $(window).resize(this.on_resize_handler);
         this.on_resize_handler();
     };
-    
+
     GridStack.prototype._trigger_change_event = function(forceTrigger) {
         var elements = this.grid.get_dirty_nodes();
         var hasChanges = false;
@@ -761,7 +761,7 @@
         this.container.remove();
         Utils.remove_stylesheet(this._styles_id);
         if (this.grid)
-            this.grid = null; 
+            this.grid = null;
     };
 
     GridStack.prototype.resizable = function(el, val) {
@@ -959,7 +959,7 @@
 
     GridStack.prototype._set_static_class = function() {
         var static_class_name = 'grid-stack-static';
-        
+
         if (this.opts.static_grid === true) {
             this.container.addClass(static_class_name);
         } else {