Fixing uninitialized constant Rake::DSL issue

Reference: http://stackoverflow.com/questions/6181312/how-to-fix-the-uninitialized-constant-rakedsl-problem-on-heroku

Error:
```
rake snorby:setup
(in /opt/snorby)
No time_zone specified in snorby_config.yml; detected time_zone: US/Central
rake aborted!
uninitialized constant Rake::DSL
```