fix(wrapper): incorporate setter and getter in one method to rule them all

One Method to find them,
One Method to bring them all and in the darkness bind them
In the Land of Mordor where the Shadows lie.

.gitignore

@@ -1,3 +1,5 @@
 .grunt
 node_modules
 components
+.idea/
+bower_components/

dist/js/bootstrap-switch.js

@@ -268,6 +268,9 @@
         if (typeof value === "undefined") {
           return this.options.wrapperClass;
         }
+        if (!value) {
+          value = $.fn.bootstrapSwitch.defaults.wrapperClass;
+        }
         getClasses = (function(_this) {
           return function(classes) {
             var c, cls, _i, _len;

src/coffee/bootstrap-switch.coffee

@@ -189,6 +189,8 @@ do ($ = window.jQuery, window) ->
     wrapperClass: (value) ->
       return @options.wrapperClass if typeof value is "undefined"
 
+      value = $.fn.bootstrapSwitch.defaults.wrapperClass if !value
+
       getClasses = (classes) =>
         unless $.isArray classes
           return "#{@options.baseClass}-#{classes}"