Setup configuration from a YAML file instead of ENV variables to provide more flexibility

[deshetti]

As suggested by @utkarshx, it is probably a good time now to be able to set up the configuration for Dega using a YAML file to provide configuration options in a more meaningful way. Viper allows us to do so and need to give a thought to how we should structure the configuration.

Configuration through a YAML file is still possible with the current setting. If I am not mistaken DEGA_SAMPLE_ENVIRONMENT is similar to:

dega:
   sample:
      environment:

Will have to confirm the above.