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.
Removing all JS changes bar this one would break the login / registration changes I am proposing. In which case there would be no point merging any of the non-JS files submitted with this patch. 

If you would care to review and test the patch in full (I pushed an update this morning to refine it further) and provide feedback regarding the new login system proposed - notes about the UI, functionality, and user options would be great - we can then go into detail about what changes would be needed to merge it into the master branch.