Partial fix for #793 and merge users/views fields

- Added setting for default timezone to be used when registering new
users ('site.default_user_timezone' in
/application/config/application.php)
- Setup the user forms (register/profile/user_form) to use a common view
for shared fields (\users\views\user_fields.php)
Fix #53 Auto Load of languages failure

Copied handling of arrays as first argument to MY_Lang->load() method
from MX_Lang->load() method.
Fix error support: user language/timezone fields