Capybara added to demonstrate vulnerabilities.

Adding Capybara to verify replay-ability of hacking vulnerabilities. I
imagine these may want to be kept on a different branch for QA and
educational purposes, but not distributed with master when forked.

This commit also includes demonstrating the SQL Injection vulnerability.
Added command injection Capybara spec.
XSS Capybara spec added.
Broken Authorization specs added.
Insecure Direct Object Reference spec added.

This includes two scenarios - the work_info one mentioned in the
tutorials, but also one allowing downloading of source code, which may
belong somewhere else as I haven't worked through all the tutorials yet.
Merge pull request #47 from chrismo/capybara

Capybara added to demonstrate vulnerabilities.