RPR Cp view reviews

issue #12 
Since this feature is essentially part of the "User views a bus' page" feature, you could just modify the spec for that feature to expect the page to contain all the bus' reviews.  This is fine, but here's how you'd modify the `user_views_a_bus_page_spec.rb`:

```ruby
feature "User views list of buses", %{
  As a user I want to view a bus page
  So that I can see the bus' information
  } do

  scenario "views bus page" do
    ride = FactoryGirl.create(:ride)
    reviews = FactoryGirl.create_list(:review, 3, ride: ride) # creates 3 reviews associated with the ride object we just made
    bus = ride.bus

    visit bus_path(bus)
    expect(page).to have_content bus.number
    expect(page).to have_content bus.inbound
    expect(page).to have_content bus.outbound

    # expect bus reviews to appear
    reviews.each do |review|
      expect(page).to have_content review.body
    end
  end
```