v0.3.3

1. Refactored code base
2. Added 'unrendered' login functionality for the login widget
3. Added 'key' parameter to all widgets to avoid duplicate WidgetID errors
4. Added 'callback' parameter to all widgets to invoke developer provided function on successful widget submission
5. Added 'captcha' to select widgets
6. Allowed developer to upload empty credentials dict with no users
7. Allowed developer to disable automatic hashing with the 'auto_hash' parameter in the Authenticate class
8. Added 'Hasher.hash_passwords' to allow the developer to pre-hash all plain-test passwords in the credentials
9. Allowed user to register with email as username
10. Enforced strong password requirements for new users