Description:
    Generates a migration file for deleting and a creating a DynamoDB
    sessions table, and a configuration file for the session store.

Example:
    rails generate dynamo_db:session_store_migration <MIGRATION_NAME>

    This will create:
        db/migrate/#{VERSION}_#{MIGRATION_NAME}.rb
        config/dynamo_db_session_store.yml

    The migration will be run when the command rake db:migrate is run
    in the command line.