Thank you very much for this plug in. Is there a way to provide `optgroups` for the value when the input is `select`? Something like this I am hoping ``` values: [ { 'value' : 'one', 'text': 'Un', 'optgroups': 'Group 1' }, { 'value' : 'two', 'text': 'Deux', 'optgroups': 'Group 1' }, { 'value' : 'three', 'text': 'Trois', 'optgroups': 'Group 2' } ] ```