Description:
    The settings migration generator creates a migration for the settings plugin.

    The generator takes a migration name as its argument.  The migration name may be
    given in CamelCase or under_score.  'add_settings_table' is the default.

    The generator creates a migration class in db/migrate prefixed by its number
    in the queue.

Example:
    ./script/generate settings_migration

    With 4 existing migrations, this will create an AddSettingsTable migration in the
    file db/migrate/005_add_settings_table.rb