correct local env setup and replace io.ioutil.* by os.*

[lanphan]

Hello,

I've just new to Sisu network and try to set it up. I start with this dheart repo first but got some problems:

• script to generate config file go run core/config/gen-localhost/main.go got several issues below and I fixed them
• some deprecated ioutil.Read/Write methods, I use os.* instead

I still cannot run it just because there is still no sisu server running 16:28:23.85 Cannot ping sisu, err = Post "http://0.0.0.0:25456": dial tcp 0.0.0.0:25456: connect: connection refused , maybe I need to start with sisu repo first

By the way, please help to review and check that my update is useful for your project or not.