Add support for command line config options

[efirs]

Currently instances can be configured with decentralized config files or centralized config in the state database.

We need to add ability to configure instances by command line parameters.

[aman-bansal]

Hi @efirs, I would love to contribute to this project. But there are no community guidelines regarding contributing to this project. So are contributions welcome? If yes is there anything I need to take care of?

Sorry I am commenting this on issue but couldn't find another way to connect. I would love to take this issue as my first :).

[efirs]

Hi, @aman-bansal, thanks for expressing interest in contribution. Contributions are welcome! Just go ahead and file a PR.

[efirs]

We need to consider integrating with https://github.com/spf13/viper