Wrong foreign keys in schema

Patch applies cleanly and looks good to me. Seems like a minor typo in the code, there is no "user" table.

Foreign keys are explained here: http://drupal.org/node/146939

'foreign keys': An associative array of foreign keys ('keyname' => specification). Each specification is an array with 'table' and 'columns' elements that form a foreign key for the table.

'table' is a string specifying the foreign table, and 'columns' is an associative array in the format 'source_column' => 'target_column'.

Note: Foreign key definitions were added in Drupal 7 for documentation purposes only, and do not modify the database.

Thanks for reviewing! Setting to RTBC; will commit later.

Committed. Thanks!