Allowed addressable 2.4+ to work with json-schema

I've had to change one of the specs because of this. It seems that
addressable now raises an error if you parse a uri that looks like a
json text, which was one of our test cases.

This fixes and supersedes #301

CHANGELOG.md

@@ -10,6 +10,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 - Readme was converted from textile to markdown
+- Updated addressable dependency to 2.4.0
 
 ## [2.6.0] - 2016-01-08
 

json-schema.gemspec

@@ -23,5 +23,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency "webmock"
   s.add_development_dependency "bundler"
 
-  s.add_runtime_dependency "addressable", '~> 2.3.8'
+  s.add_runtime_dependency "addressable", '>= 2.4'
 end

test/test_initialize_data.rb

@@ -40,7 +40,7 @@ def test_parse_hash_string
 
     assert(JSON::Validator.validate(schema, data, :json => true))
 
-    assert_raises(JSON::Schema::JsonLoadError) { JSON::Validator.validate(schema, data, :uri => true) }
+    assert_raises(JSON::Schema::UriError) { JSON::Validator.validate(schema, data, :uri => true) }
   end
 
   def test_parse_json_string