Log Message:
Update ruby-activerecord to 2.1.1.

Changes:

* Set config.active_record.timestamped_migrations = false to have
  migrations with numeric prefix instead of UTC
  timestamp. #446.

* Fixed that create database statements would always include "DEFAULT
  NULL" [#334]

* change_column_default preserves the not-null constraint.  #617

* Add :tokenizer option to validates_length_of to specify how to split
  up the attribute string. #507. Example :

  # Ensure essay contains at least 100 words.
  validates_length_of :essay, :minimum => 100, :too_short => "Your
  essay must be at least %d words."), :tokenizer => lambda {|str|
  str.scan(/\w+/) }

* Always treat integer :limit as byte length.  #420

* Partial updates don't update lock_version if nothing changed.  #426

* Fix column collision with named_scope and :joins.  #46

* db:migrate:down and :up update schema_migrations.  #369

* PostgreSQL: support :conditions => [':foo::integer', { :foo => 1 }]
  without treating the ::integer typecast as a bind variable.

* MySQL: rename_column preserves column defaults.  #466

* Add :from option to calculations.  #397

* Add :validate option to associations to enable/disable the automatic
  validation of associated models. Resolves #301.

* PostgreSQL: use 'INSERT ... RETURNING id' for 8.2 and later.

* Added SQL escaping for :limit and :offset in MySQL