Currently have static priority of what key is used irregardless of
whether a flag was provided via CLI or in config. This makes it
impossible to override some of the config settings. While we could try
to check if the key is provided by CLI by binding CLI flag under to
viper under a different name the same problem would occur for config/environment
variables. Fixing all of this with current set of keys is too complicate.
In this commit we revert changes from #610 and use a single flag for all types of keys.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
