chg: [plugin:chosen] avoid creating useless chosen widget (mistic100#743)

Prevent the creation of an glitchy empty chosen widget in case of a select containing only one value.

Author: mokaddem

src/plugins/chosen-selectpicker/plugin.js

@@ -23,7 +23,9 @@ QueryBuilder.define('chosen-selectpicker', function(options) {
     });
 
     this.on('afterCreateRuleOperators', function(e, rule) {
-        rule.$el.find(Selectors.rule_operator).removeClass('form-control').chosen(options);
+        if (e.builder.getOperators(rule.filter).length > 1) {
+            rule.$el.find(Selectors.rule_operator).removeClass('form-control').chosen(options);
+        }
     });
 
     // update selectpicker on change