Master key should not be input with env or args

[zhongguozhang]

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"

[auxten]

You can try -password to pass a master key.
This is vulnerable and will be changed to use an interactive way to let user input master key in the console.

[zhongguozhang]

测过了， ./cql -config conf/config.yaml -get-balance -password xxxxxx 这样可以

[auxten]

Fixed at #284