Add ISO timestamp

[oubiwann]

This needs to e converted to LFE (taken from http://schemecookbook.org/Erlang/TimeISO8601):

iso_8601_fmt(DateTime) ->
    {{Year,Month,Day},{Hour,Min,Sec}} = DateTime,
    io_lib:format("~4.10.0B-~2.10.0B-~2.10.0B ~2.10.0B:~2.10.0B:~2.10.0B",
        [Year, Month, Day, Hour, Min, Sec]).

1> CurrDateTime = erlang:localtime().
{{2004,8,28},{1,19,37}}
2> {{Year,Month,Day},{Hour,Min,Sec}} = CurrDateTime.
{{2004,8,28},{1,19,37}}
3> io:fwrite("~s\n",[iso_8601_fmt(erlang:localtime())]).
2004-08-28 01:48:48