version 1.8

bug fix, be able to handle error response from alipay server

load key immediately once Alipay instance created

Do encryption/decryption with

initialize alipay instance with key string

convert appid from int to str by force

alipay.trade.fastpay.refund.query

docs updated for 1.3.0

api_alipay_open_auth_token_app, no need to pass app_auth_code