add production stage for deployment via capsitrano

Added production.rb file to support deployment to "production" environment.
Removed non-default setting in config/deploy.rb per discussion with Scot Dalton.
@jgpawletko, to protect us against ourselves, I'm thinking the branch should just be
```ruby
set :branch, 'master'
```
The assumption, of course, is that the master branch is always production ready.