- Fix "uri" check, so that it only accept ASCII characters. Note that this
   fix might be an undesired change for your application. If so, then update
   the "uri" format in your schema to "iri".
 - Fix "hostname" format check, so it does not require a valid TLD
 - Fix validating draft-07 schema against itself #144
 - Add support for more formats in JSON Schema draft-6 and 7: date, idn-email,
   idn-hostname, iri, iri-reference, json-pointer, relative-json-pointer, time,
   uri-reference and uri-template.
 - Add support for more keywords in draft-07
   * 6.4.6. Arrays - contains
   * 6.5.8. Objects - propertyNames
   * 6.6.1. Objects - if
   * 6.6.2. Objects - then
   * 6.6.3. Objects - else