Revision 1771188

[tools] review DateTool new formatting styles.

Here's the new proposed implementation:

 * 'short', 'medium', 'long', 'full' (from java.text.DateFormat), optionally suffixed by '_date' or '_time' to get a date-only or time-only format        
 * 'iso' for extended ISO 8601 without time zone (ex: '2016-11-24T10:27:30'), optionally suffixed by '_date' or '_time' to get a date-only or time-only format</li>
 * 'iso_tz', like 'iso' with time zone offset (ex: '2016-11-24T10:27:30+01:00'), optionally suffixed by '_time' to get a time-only format ('10:27:30+01:00')</li>
 * 'intl', like 'iso' but with a space separator between date and time (ex: '2016-11-24 10:27:30'), optionally suffixed by '_date' or '_time' to get a date-only or time-only format</li>
 * 'intl_tz', like 'intl' but with the time zone short id suffixed after another space (ex: '2016-11-24 10:27:30 CET'), optionally suffixed by '_time' to get a time-only format ('10:27:30+01:00')</li>
 * a custom format, as specified in java.text.SimpleDateFormat