When I see `install_gems(is_ci ? 'development' : '')` I think it install development gems if `is_ci` is true, but actually it does not.

I believe this is the case when we should use ruby 2.0 named parameters:

```ruby
def install_gems(without: 'production staging')
  ...
end

...

install_gems(without: is_ci ? 'development' : '')
```