Upgrade clearance passwords to authlogic

# if you look in clearance/lib/clearance/user.rb you can see the encryption method
#
#  def encrypt(string)
#    generate_hash("--#{salt}--#{string}--")
#  end
#
# lib/clearance_crypto.rb
class ClearanceCrypto
  def self.encrypt(*tokens)
    Digest::SHA1.hexdigest("--#{tokens[1]}--#{tokens[0]}--")
  end

  def self.matches?(crypted_password, *tokens)
    # tokens = ["plain text password", "password_salt"]
    # crypted_password = crypted_password in db
    encrypt(*tokens) == crypted_password
  end

end

# your model that needs authentication
# app/models/user.rb
class User < ActiveRecord::Base
  acts_as_authentic do |c|
    c.transition_from_crypto_providers = ClearanceCrypto,
    c.crypto_provider = Authlogic::CryptoProviders::Sha512
  end
end

# If you you have problems logging in make sure you don't have any of the "magic"
# fields set to something that would deny a login such as an "active" field set to 
# 0. You can also turn off magic fields too and session management within 
# authlogic.