Master key should not be input with env or args #106
Description
查看自己的钱包余额时，如果之前有输入master key，则提示失败。
错误提示如下：
./cql -config conf/config.yaml -get-balance
ERRO[0000] decrypt private key error caller="privatekeystore.go:50 crypto/kms.LoadPrivateKey"
INFO[0000] load private key failed: invalid PKCS#7 padding caller="privatekeystore.go:90 crypto/kms.InitLocalKeyPair"
ERRO[0000] unexpected error while loading private key: invalid PKCS#7 padding caller="privatekeystore.go:109 crypto/kms.InitLocalKeyPair"
ERRO[0000] init covenantsql client failed: invalid PKCS#7 padding caller="main.go:196 main.main"