As for http2time, but parses the ISO 8601 formats:
- 1994-02-03 14:15:29 -0100
- ISO 8601 format
1994-02-03 14:15:29 -- zone is optional
1994-02-03 -- only date
1994-02-03T14:15:29 -- Use T as separator
19940203T141529Z -- ISO 8601 compact format
19940203 -- only date