Update config...secret_token.rb to be secure if public

The config/initializers/secret_token.rb page created by default would be insecure to include in any public repository (such as this one). A perfect solution to this problem has been created by Michael Hartl. That solution was used to fix this problem. The original source can be found here:

http://ruby.railstutorial.org/chapters/static-pages#code-secret_token