Fixed unnecessary scopes mutation

The issue due to the mutated scopes popped up in Swagger-UI: swagger-api/swagger-ui#2483

Author: frol

lib/client.js

@@ -310,7 +310,7 @@ SwaggerClient.prototype.buildFromSpec = function (response) {
       for(var ext in securityDefinition) {
         helpers.extractExtensions(ext, securityDefinition);
         if (ext === 'scopes') {
-          var scopes = securityDefinition[ext];
+          var scopes = _.cloneDeep(securityDefinition[ext]);
           if(typeof scopes === 'object') {
             scopes.vendorExtensions = {};
             for (var s in scopes) {