add list api keys for account, track last_used for api_keys

db/jambones-sql.sql

@@ -56,6 +56,8 @@ token CHAR(36) NOT NULL UNIQUE ,
 account_sid CHAR(36),
 service_provider_sid CHAR(36),
 expires_at TIMESTAMP,
+last_used TIMESTAMP ON UPDATE NOW(),
+created_at TIMESTAMP DEFAULT NOW(),
 PRIMARY KEY (api_key_sid)
 ) ENGINE=InnoDB COMMENT='An authorization token that is used to access the REST api';