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.

(I also have seen the starter work with gauntlt, only after doing up this
code. Since this attack didn't require (though could have used) some of
the tooling supported by gauntlt, I decided to leave this as-is. My goal
is to continue working through automating the attacks, time permitting.
Be interested in your feedback on using Capybara for some of these).