name validation should allow nil in the length check by default

Regards to user.rb

  validates_format_of       :name,     :with => Authentication.name_regex,  :message => Authentication.bad_name_message, :allow_nil => true
  validates_length_of       :name,     :maximum => 100

We already allow nil names in the format validation, why not allow nils in the validates_length_of?

This way you can store null values of names in the databases and can also change the migration to do the same thing.