let authlogic define the username regex.

app/models/users/user.rb

@@ -83,8 +83,6 @@ class User < ActiveRecord::Base
     c.session_class = Authentication
     c.validates_uniqueness_of_login_field_options = { :message => :username_taken }
     c.validates_length_of_login_field_options     = { :minimum => 1, :message => :missing_username }
-    c.merge_validates_format_of_login_field_options(:with => /\A[a-zA-Z0-9_-]+\z/)
-
     c.validates_uniqueness_of_email_field_options = { :message => :email_in_use }
     c.validates_length_of_password_field_options  = { :minimum => 0, :allow_blank => true, :if => :require_password? }
     c.ignore_blank_passwords = true