Run tests with rake ci for continuous integration

Per https://github.com/rubyrogues/rubyfriends/pull/30#issuecomment-16442455

Also, moves application.yml out of version control.

`rake ci` will copy application.example.yml to application.yml and run the default rake task (which runs the tests)

Now I can customize my application.yml and not worry about committing it.

Also, as an aside, added `rake bootstrap` that copies over the config and migrates the database. (does the database.yml need to be in version control?)