Add verification for user input

[kadel]

We should verify values from user.
For example if we are asking for port, we should verify that it is string, and it is in sensible range etc...

[surajssd]

I feel, wouldn't that be a double work, I mean converters' code going ahead does that checkup right?

[kadel]

When you are injecting values to Config struct validation has already been done.

[surajssd]

Yeah true.