[Rake] Fix `rake` by removing obsolete require statement
[Security] Add Brakeman security vulnerability scanner

Generate a HTML report of security vulnerabilities by running:

    bundle exec rake brakeman:run[log/brakeman.html]

Here's what the scan report looks like: http://jsbin.com/ekecec/1.

See http://brakemanscanner.org/ for details.
Merge pull request #597 from jamestyj/release/pebbles/master-brakeman

[Security] Add Brakeman security vulnerability scanner
added some logging messages