Provide ability to add divider to menu.

js/bootstrap-multiselect.js

@@ -143,6 +143,7 @@
             ul: '<ul class="multiselect-container dropdown-menu"></ul>',
             filter: '<div class="input-group"><span class="input-group-addon"><i class="glyphicon glyphicon-search"></i></span><input class="form-control multiselect-search" type="text"></div>',
             li: '<li><a href="javascript:void(0);"><label></label></a></li>',
+            divider: '<li class="divider"></li>',
             liGroup: '<li><label class="multiselect-group"></label></li>'
         },
 
@@ -217,8 +218,15 @@
                     this.createOptgroup(element);
                 }
                 else if (tag === 'option') {
+
+                    if ($(element).data('role') === 'divider') {
+                        this.createDivider();
+                    }
+                    else {
                         this.createOptionValue(element);
                     }
+
+                }
                 // Other illegal tags will be ignored.
             }, this));
 
@@ -429,6 +437,12 @@
             }
         },
 
+        // Create divider
+        createDivider: function(element) {
+            var $divider = $(this.templates.divider);
+            this.$ul.append($divider);
+        },
+
         // Create optgroup.
         createOptgroup: function(group) {
             var groupName = $(group).prop('label');