`URI.parse` chokes on CGI-unescaped unicode chars. `Addressable::URI.parse` doesn't. We're already using Addressable downstream, so just promote it to first-class required gem and use it.

This smells bad and I would like to rethink it.

# Conflicts:
#	Gemfile
#	Gemfile.lock

# Conflicts:
#	app/controllers/api_controller.rb
#	test/controllers/oembed_controller_test.rb
#	test/lib/statistics_test.rb