Addressable is a replacement for the URI implementation that is part of Ruby's standard library. It more closely conforms to the relevant RFCs and adds support for IRIs and URI templates.

You know what to do:

sudo gem install addressable

Alternatively, you can:

git submodule add git:// vendor/gems/addressable

Addressable works in Ruby 1.8.x, 1.9.x, and JRuby.