Add support for JodaTime DateTimes

[mhalverson]

Added support for JodaTime DateTime objects (assumes they're being serialized as longs).

The only change from the front-end is the addition of a new ColumnType called "JodaDateTime". You can both read and edit cells of this ColumnType, just like a "normal" DateTime.

Implementation is in the same manner as the implementation for normal DateTimes.

[icher-g]

Hi,

I simplified and a little bit generalized your solution. In other words I changed the DateTime type to be a DateAsString type meaning that the date time is represented as a string and added another one called DateAsLong to support any date time represented as long. I didn’t want to be dependent on joda so I used regular Date class.

Best Regards,
Igor Cher.