Update bootstrap-datetimepicker.js

fix parts parser in case of date as number (i.e. year picker only)

E.g.:

$('.year-picker', element).datetimepicker({
				format: "yyyy",
				weekStart: 1,
				todayBtn: true,
				autoclose: true,
				todayHighlight: true,
				startView: 4,
				minView: 4,
				maxView: 4,
				forceParse: true,
				language: App.language
			});

Will now works if we use only years