Updated the common test suite
Merge pull request #191 from iainbeeston/update_common_test_suite

Updated the common test suite
Remove unused Schema#base_uri method
Remove "no dependencies" claim from README
Merge pull request #193 from pd/rm-unused-method

Remove unused Schema#base_uri method
Merge pull request #194 from pd/readme-dependencies

Remove "no dependencies" claim from README
JSON::Schema::Loader
Wedge JSON::Schema::Loader into place in Validator

Conflicts:
	lib/json-schema/validator.rb
Document JSON::Schema::Loader in the README

Prolly got some textile syntax a bit wrong, and the link to the yard
docs won't work prior to this being merged.
Revert some unnecessary changes

I'll submit a separate PR to add pry (and pry-byebug) as dependencies in
the Gemfile.

Reverted some changes I made to attributes/ref.rb that would conflict
with #186.