Sets the model associated with this proxy. This will only usually be called by a Store

@param {String/Ext.data.Model} model The new model. Can be either the model name string,
or a reference to the model's constructor
@param {Boolean} setOnStore Sets the new model on the associated Store, if one is present
function(model, setOnStore) {
        var me = this;
        
        me.model = Ext.ModelManager.getModel(model);

        me.setReader(this.reader);
        me.setWriter(this.writer);

        if (setOnStore && me.store) {
            me.store.setModel(me.model);
        }
    }