oauth update

db/migrate/20161108224701_add_unique_id_to_users.rb

@@ -0,0 +1,21 @@
+class AddUniqueIdToUsers < ActiveRecord::Migration[5.0]
+  def up
+    add_column :users, :encrypted_id, :string
+
+    User.all.each do |user|
+      user.set_encrypted_id
+      user.save!
+    end
+
+    change_column_null :users, :encrypted_id, false
+
+    add_index :users, :encrypted_id, unique: true
+    remove_index :users, :username
+  end
+
+  def down
+    add_index :users, :username, unique: true
+    remove_index :users, :encrypted_id
+    remove_column :users, :encrypted_id
+  end
+end