JSON does not define any representation for encoding date/time
information.

It *appears* that people tend to use ISO-8601 for them [1].
May be that's what Go does.
Note that the documentation for the encoding/json package does not
mention dates and times at all.
1.http://en.wikipedia.org/wiki/ISO_8601

http://blog.charmes.net/2015/08/json-date-management-in-golang_7.html