Christoph Büscher 6acbefe3f7 Add tests for alternative ways of writing zero offset timezones
According to ISO 8601, a time zone offset of zero, can be stated numerically as
"+00:00", "+0000", or "00". The Joda library also seems to allow for "-00:00",
"-00" and "-0000". This adds some test to the DateMathParserTests that check
that we also conform to this.

Closes #21320
2016-11-04 12:24:40 +01:00
..
2016-10-07 13:05:30 -05:00