Save track files in new Sound model:

* Consolidate migrations
* Add Sound model. Each sound can belong to a track and contains
  informations about one sound file.

db/migrate/20110915211845_initial_schema.rb

@@ -0,0 +1,48 @@
+class InitialSchema < ActiveRecord::Migration
+  def up
+
+    create_table :playlists do |t|
+      t.integer  :user_id
+      t.string   :name
+
+      t.timestamps
+    end
+
+    create_table :sessions do |t|
+      t.string   :session_id, :null => false
+      t.text     :data
+
+      t.timestamps
+    end
+
+    add_index :sessions, :session_id
+    add_index :sessions, :updated_at
+
+    create_table :tracks do |t|
+      t.string   :name
+
+      t.timestamps
+    end
+
+    create_table :users do |t|
+      t.string   :email
+      t.string   :password_hash
+
+      t.timestamps
+    end
+
+    add_index :users, :email, :unique => true
+
+  end
+
+  def down
+    drop_index :sessions, :session_id
+    drop_index :sessions, :updated_at
+    drop_index :users, :email
+
+    drop_table :playlists
+    drop_table :sessions
+    drop_table :tracks
+    drop_table :users
+  end
+end