Log Message:
Update ruby-sequel pacakge to 3.27.0.

=== 3.27.0 (2011-09-01)

* Add support for native prepared statements to the tinytds adapter
  (jeremyevans)

* Add support for native prepared statements and stored procedures to the
  mysql2 adapter (jeremyevans)

* Support dropping primary key, foreign key, and unique constraints on MySQL
  via the drop_constraint :type option (jeremyevans)

* Add Sequel::SQLTime class for handling SQL time columns (jeremyevans)

* Typecast DateTime objects to Date for date columns (jeremyevans)

* When typecasting Date objects to timestamps, make the resulting objects
  always have no fractional date components (jeremyevans)

* Add Model.dataset_module for simplifying many def_dataset_method calls
  (jeremyevans)

* Make prepared_statements_safe plugin work on classes without datasets
  (jeremyevans)

* Make Dataset#hash work correctly when referencing SQL::Expression instances
  (jeremyevans)

* Handle allowed mass assignment methods correctly when including modules in
  classes or extending instances with modules (jeremyevans)

* Fix Model#hash to work correctly with composite primary keys and with no
  primary key (jeremyevans)

* Model#exists? now returns false without issuing a query for new model
  objects (jeremyevans)