Release 1.1.6.

* Set output encoding to UTF-8 in Writer and CLI for JRuby.
* Improve RDF generation from vocabulary terms for non-distinctive attributes.
* Date/Time/DateTime timezone updates:
  * Add #has_timezone? (#has_tz?) to Date, Time and DateTime.
  * Add #tz to Date, used for recovering timezone from lexical representation.
  * Date canonicalization does not normalize to UTC per XSD canonicalization instructions.
* Represent Literal::Time using ::DateTime instead of ::Time, as ::Time looses any declared timezone.
* Add Time#tz and Date#tz.
* Added Literal#humanize defaulting to #to_s. Special implementations for Date, Time, and DateTime.
* Update for schema.org 1.91
* Add response headers to Util::File::RemoteDocument.
* Also includes `#etag` and `#links`.
* Links are parsed using the link_header gem, allowing them to be searched.
* Add response headers to Util::File::RemoteDocument.
* Also includes `#etag` and `#links`.
* Links are parsed using the link_header gem, allowing them to be searched.
Change behavior of base_uri after 303 redirect to be consistent with JSON-LD tests: base_uri is updated to the new document location.
Use RestClient in Util::File.open_file, which can enable client-side caching.
Util::File.open_file now uses RestClient only if it is previously defined, otherwise it falls back to Net::HTTP.
Don't require rest_client.
Require rest-client in Util::File spec.
Fix accessor error on RestClient response error.
Make SSL verification subject to :verify_none flag to Util::File.open_file, previously this was always true.
Update method signature for Vocabulary#resond_to? to include optional second parameter.
This resolves issue #166.
Update schema.org vocabulary definition for its 2.0 release.
Version 1.1.7.
Release 1.1.7

* RDF::Util::File:
  * now returns or yields a RemoteDocument, which is based on StringIO.
  * provides #base_uri, #content_type, #charset, #last_modified, #headers, #code, #content_encoding, #links, and #etag accessors.
  * base_uri always updated on 3xx redirect, previously did not for code 303.
  * If loaded, uses RestClient for retrieving remote resources rather than Net::HTTP. This allows for client-side caching if the rest-client-components gem is also loaded, and `RestClient.enable Rack::Cache` is set.
  * Added :verify_none option, which turns off SSL verification if set; previously, it was the default.
* Updated schema.org vocabulary definition to _venkman_/2.0.