Reset _ids for rebuild

lib/model-definition.js

@@ -164,7 +164,7 @@ ModelDefinition.prototype.idName = function() {
     var id = this.ids()[0];
     if(this.properties.id && this.properties.id.id) {
         return 'id';
-    }
+    } else {}
     return id && id.name;
 };
 
@@ -256,6 +256,7 @@ ModelDefinition.prototype.build = function (forceRebuild) {
     if(forceRebuild) {
         this.properties = null;
         this.associations = [];
+        this._ids = null;
     }
     if (this.properties) {
         return this.properties;