Update specs to new rspec syntax

spec/views/playlists/index.html.haml_spec.rb

@@ -9,16 +9,16 @@ describe 'playlists/index' do
 
   it 'displays a list of playlists' do
     render
-    rendered.should have_selector('ul>li', text: 'Electro')
+    expect(rendered).to have_selector 'ul>li', text: 'Electro'
   end
 
   it 'displays a link to create a new playlist' do
     render
-    rendered.should have_selector('a', text: 'Create playlist')
+    expect(rendered).to have_selector 'a', text: 'Create playlist'
   end
 
   it 'displays playlists as links' do
     render
-    rendered.should have_selector('a', text: 'Electro')
+    expect(rendered).to have_selector 'a', text: 'Electro'
   end
 end