Implement Authentication

Install Devise, generate Devise User model
Add Username to User model

Allow users to login using either their username or their email.
Add Devise views for manual testing purposes.
Add and install FactoryGirl and RSpec
Add User factory and spec
Add and install Doorkeeper. Integrate with Devise.
Add Item Resource

Create Item Model
Associate Item with User
Create API V1 route /v1/<resource>
Create API access to Item
Create Item Factory
Create Item Spec
Add Item & User Resource Tests

Tests both authorized and unauthorized requests.