Support all String `format` keys

[mwildehahn]

• [ ] date-time, eg: 2018-11-13T20:20:39+00:00
• [ ] time, eg: 20:20:39+00:00
• [ ] email, eg: RFC 5322, section 3.4.1
• [ ] idn-email" RFC 6531
• [ ] hostname RFC 1034, section 3.1
• [ ] idn-hostname RFC5890, section 2.3.2.3
• [ ] ipv4 RFC 2673, section 3.2
• [ ] ipv6 RFC 2373, section 2.2
• [ ] uri RFC3986
• [ ] uri-reference RFC3986, section 4.1
• [ ] iri RFC3987
• [ ] iri-reference RFC3987
• [ ] uri-template RFC6570
• [ ] json-pointer RFC6901
• [ ] "relative-json-pointer https://tools.ietf.org/html/draft-handrews-relative-json-pointer-01
• [ ] regex ECMA 262