Don't use `sudo` to npm install

[olizilla]

I know that sudo npm install -g <some module> is the common solution to the fact that the install sets bobbins permissions on the node_modules folder, but I don't think security-adventure should be recommending that, given an npm install can do just about anything to your system.

https://github.com/toolness/security-adventure/blob/c3fa8c2bf9d19e66fc9420d6f1ec1f1e32eb3ce3/README.md#via-npm

Just a thought. Awesome work, regardless!