Override configuration with mode specific cofiguration.
Don't hardcode fallback value for configuration.

Hardcoded fallback values are redundant because fallback values are already
given in application.conf.
Extract config related methods from Global to BeyondConfiguration.
Use mode specific configurations.

application.conf and zoo.cfg now have mode specific configurations:
application.{mode}.conf andz zoo.{mode}.cfg. Here mode can be dev, prod and
test.