Update dependencies.

Author: gkellogg

.travis.yml

@@ -1,6 +1,8 @@
 language: ruby
 bundler_args: --without debug
 script: "bundle exec rspec spec"
+before_install: "gem update --system"
+
 env:
   - CI=true
 gemfile:
@@ -10,6 +12,7 @@ rvm:
   - 2.2
   - 2.3
   - 2.4
+  - 2.5
   - jruby-9
   - rbx-3
 cache: bundler

Gemfile

@@ -9,7 +9,7 @@ gem "jruby-openssl",      platforms: :jruby
 gem "nokogiri",           '~> 1.8'
 
 group :development, :test do
-  gem 'ebnf',           git: "https://github.com/gkellogg/ebnf",                branch: "develop"
+  gem 'ebnf',           git: "https://github.com/dryruby/ebnf",                 branch: "develop"
   gem 'rdf-isomorphic', git: "https://github.com/ruby-rdf/rdf-isomorphic",      branch: "develop"
   gem 'rdf-spec',       git: "https://github.com/ruby-rdf/rdf-spec",            branch: "develop"
   gem 'rdf-turtle',     git: "https://github.com/ruby-rdf/rdf-turtle",          branch: "develop"

Gemfile-pure

@@ -9,7 +9,7 @@ gem "jruby-openssl",      platforms: :jruby
 #gem "nokogiri",           '~> 1.8'
 
 group :development, :test do
-  gem 'ebnf',           git: "https://github.com/gkellogg/ebnf",                branch: "develop"
+  gem 'ebnf',           git: "https://github.com/dryruby/ebnf",                 branch: "develop"
   gem 'rdf-isomorphic', git: "https://github.com/ruby-rdf/rdf-isomorphic",      branch: "develop"
   gem 'rdf-spec',       git: "https://github.com/ruby-rdf/rdf-spec",            branch: "develop"
   gem 'rdf-turtle',     git: "https://github.com/ruby-rdf/rdf-turtle",          branch: "develop"

README.md

@@ -93,10 +93,10 @@ This is a [Ruby][] implementation of a [SPARQL][] client for [RDF.rb][].
 ## Dependencies
 
 * [Ruby](http://ruby-lang.org/) (>= 2.2.2)
-* [RDF.rb](http://rubygems.org/gems/rdf) (>= 2.0)
+* [RDF.rb](http://rubygems.org/gems/rdf) (~> 3.0)
 * [Net::HTTP::Persistent](http://rubygems.org/gems/net-http-persistent) (>= 1.4)
-* Soft dependency on [SPARQL](http://rubygems.org/gems/sparql) (>= 2.0)
-* Soft dependency on [Nokogiri](http://rubygems.org/gems/nokogiri) (>= 1.6)
+* Soft dependency on [SPARQL](http://rubygems.org/gems/sparql) (~> 3.0)
+* Soft dependency on [Nokogiri](http://rubygems.org/gems/nokogiri) (>= 1.7)
 
 ## Installation