Added Sequel migrations and models for videos and channels; Fixed database name in Rakefile and defaults config file

db/migrations/0001_add_channels_table.rb

@@ -0,0 +1,18 @@
+Sequel.migration do
+
+  up do
+    create_table(:channels) do
+      primary_key :id
+      String :name, null: false
+      String :description
+      DateTime :purchased_at
+      DateTime :created_at, default: Sequel::CURRENT_TIMESTAMP
+      DateTime :updated_at, default: Sequel::CURRENT_TIMESTAMP
+    end
+  end
+
+  down do
+    drop_table(:channels)
+  end
+
+end

db/migrations/0002_add_videos_table.rb

@@ -0,0 +1,23 @@
+Sequel.migration do
+
+  up do
+    create_table(:videos) do
+      primary_key :id
+      String :name, null: false
+      String :description
+      Integer :serial, null: false, unique: true
+      DateTime :purchased_at
+      DateTime :created_at, default: Sequel::CURRENT_TIMESTAMP
+      DateTime :updated_at, default: Sequel::CURRENT_TIMESTAMP
+    end
+
+    alter_table(:videos) do
+      add_foreign_key :channel_id, :channels
+    end
+  end
+
+  down do
+    drop_table(:videos)
+  end
+
+end