Overhauled / More Secure Cenny.js

New Cenny.js sandboxes users, so that it is impossible to access
another without its login information.

Nearly half the size as before.

New, simpler syntax (documentation coming soon).

Feature aditions:
user.switch() - switch between multible users.
user.remember() - remember current user.
user.forget() - forget current user.
user.remove() - remove current user.

Every method that connects with the backend has an optional callback
function for details.