Added new ItemComment model

db/migrations/0002_add_item_comments_table.rb

@@ -0,0 +1,20 @@
+Sequel.migration do
+
+  up do
+    create_table(:item_comments) do
+      primary_key :id
+      String :body, null: false
+      DateTime :created_at
+      DateTime :updated_at
+    end
+
+    alter_table(:item_comments) do
+      add_foreign_key :item_id, :items
+    end
+  end
+
+  down do
+    drop_table(:item_comments)
+  end
+
+end