see: http://stackoverflow.com/questions/15245307/java-simpledateformat-timezone-offset-with-minute-separated-by-colon
You can get the timezone offset formatted like +08:00
with the SimpleDateFormat in Java 7 (yyyy-MM-dd'T'HH:mm:ss.SSSXXX)
with the Joda's DateTimeFormat (yyyy-MM-dd'T'HH:mm:ss.SSSZZ)