Add basic playlists management

* Index of playlists
* Create a new playlist
* Basic playlist model with mandatory name

spec/models/playlist_spec.rb

@@ -0,0 +1,18 @@
+require 'spec_helper'
+
+describe Playlist do
+  subject { playlist }
+  let(:playlist) { Playlist.new :name => 'Electro' }
+
+  context "with valid attributes" do
+    it { should be_valid }
+  end
+
+  context "when name empty" do
+    before do
+      playlist.name = ''
+    end
+
+    it { should_not be_valid }
+  end
+end