Upgrade RSpec, Rails, remove Turnip.

- upgraded RSpec to 3.0
- upgraded Rails to 4.1.1
- replaced Turnip features with RSpec features
Would you like to change `.top-bar` selectors with other anchors? In most cases we redesign our projects and it would be very helpful to have some helper here:

```ruby
# spec/support/selectors.rb
Capybara.add_selector(:top_bar) do
  css { '.top-bar'  }
end

withing :top_bar do
  # check
end
```