Shall datetime with format=default support optional timezone offsets?

[peterdesmet]

Frictionless Framework will correctly parse the following datetimes with a format = default (datapackage.json.zip):

2013-11-23T08:30:00      # No timezone
2013-11-23T08:30:00Z     # UTC time
2013-11-23T06:30:00-0200 # Timezone offset

This is great! But according to the specs only UTC times should be supported (excluding offsets or no timezone):

default: An ISO8601 format string e.g. YYYY-MM-DDThh:mm:ssZ in UTC time

Is the more broad support intentional? Should the specs be updated to drop the in UTC time?

Originating issue: tdwg/camtrap-dp#333

[roll]

I think we def need to handle it in v2

[roll]

MERGED into #487