Finish 1.1.5.

* Fix odd case in fromRdf where rdf:nil is not used in a list, but is a vocabulary item, such as in the RDF vocabulary definition.
* Support :unique_bnodes option to make sure that randomized BNode lables are generated when flattening or writing.
* Minor update for in resource to see if a node is a node ref.
Finish rspec3.0
Add :simple_compact_iri option to only use simple terms when creating compact IRIs.
Enable SSL mode, and don't verify, when retrieving files.
Remove support for special-casing retrieval of schema.org context.
Added Context#from_vocabulary and script/gen_context to generate a JSON-LD context given an RDFS/OWL/schema.org vocabulary.
Include a base-context to define RDFS/OWL property types.
Also generate a hierarchical representation of a vocabulary (specifically schema.org).
Make loading remote context error fail, even if validate is not set.
This addresses part of issue #11.
Added :frame option to writer to specify frame to be used instead of context.
Added Context#reverse_term to find a term definition reversed from that requested.
Make Context#mappings, #mapping, and #languages private (used only in tests).
Make Context#alias and #coerce protected.
Improve some error messages when processing context.
Added Context#find_definition to find a term definition.
require openssl.
Make sure that serialized context uses strings, and not RDF::URI.
Better error messages when errors found parsing context.
Detect lists having nodes shared across different graphs, and add fromRdf test to check for this.
Version 1.1.6.
Release 1.1.6.

* Add :simple_compact_iri option to only use simple terms when creating compact IRIs.
* Enable SSL mode, and don't verify, when retrieving files.
* Added Context#from_vocabulary and script/gen_context to generate a JSON-LD context given an RDFS/OWL/schema.org vocabulary.
* Make loading remote context error fail, even if validate is not set (#11).
* Added :frame option to writer to specify frame to be used instead of context.
* Added Context#reverse_term to find a term definition reversed from that requested.
* Make Context#mappings, #mapping, and #languages private (used only in tests).
* Make Context#alias and #coerce protected.
* Added Context#find_definition to find a term definition.
* Detect lists having nodes shared across different graphs, and add fromRdf test to check for this.