Overhaul the user registration / login system.

Changes include:

- When registering, only ask for email and password.
- Instead of an individual username, set the username to the user email when registering (streamlines registration process)
- Add honeypot to user registration process (additional security)
- When registering, we do additional checks that the email/username doesn't already exist before registering
- register_new_user() replaced with wp_create_user() due to how Multsite handles new registration emails (password not automatically sent). This allows users to login straight away. I would look at a custom email verification process option.
- Remove username ajax checks and join with email check
- Add nonce to login and signup forms (additional security)
- Swap out wp_login_form() for ap_login_form() function
- When registering, if username already exists it will prompt them to login (TODO, should point to custom reset password interface in the future)
- When logging on, allow wp_signon() to decide if the cookie it sets should be secure or not.
- Fix link color in the ap-message-item box
- Add a little more padding to the login / registration boxes
- On hover, add a cursor to the login accordion
- When deactivating the login accordian (unchecking) make sure it hides the box
- jQuery.delegate (should become .live as .delegate is depreciated) the .ap-open-modal so we can dynamically add prompts to login modal from the registration modal when email exist validation is false.
- Ensure all modal get closed when a new modal opens.
I had a look at adding a captcha to the registration form but it won't display two captchas easily - apparently you need to destroy the active captcha before you render another. I've left this out for the time being.