For an overview of the need-o-tron visit Richard Pope's introductory blog post
Need-o-Tron is a Rails 3.1 application. It is built with ruby 1.9.2 and isn't guaranteed to work with any previous versions. To get up and running you'll need ruby and bundler installed. It should then just be a case of running:
bundle install
rake db:setup
rails server
To make it work properly you'll need to be running a correctly configured instance of solr. We're working on opening up more of our configuration files but for now the best way to get the correct solr schema is via this gist
Need-o-tron designed to work as part of a suite of applications, authenticating against an OAuth provider such as Sign-on-o-tron
It does that via the GDS-SSO gem. See that project's README for configuration details. It's an OAuth2 provider, and you could alternatively use any other OAuth2 provider.
If you don't want to authenticate against a separate app there's also a basic strategy for development use that will simply use the first user in your database. To set that up you'll want something like:
% rails console
User.create(:name => 'First User', :email => '[email protected]', :uid => 1)
exit