Similar to time.strftime, but returns unicode.
Decodes the time representation returned by time.strftime according to the character encoding as determined by the current locale.
format: str or unicode, a time format string t: optional, if given: tuple, datetime.datetime, or datetime.time
If t is omitted, the current time is used. If t is a tuple, it must be a valid time tuple as accepted by time.strftime().
returns unicode