Mapper: Date format - allow for multiple formats using '||' separator

[kimchy]

The format in the date format to allow for multiple date formats. This is handy for example to define a format similar to this: yyyy/MM/dd HH:mm:ss||yyyy/MM/dd. The "printing" from the millisecond back to a string will use the first format.

[kimchy]

Mapper: Date format - allow for multiple formats using '||' separator, closed by fdf6eb9.

[clintongormley]

Nice solution! Thanks