Enhance the error reporting

Since daemon startup error will be often related to socket errors, so it
makes sense to change the original reporting:

  Error when starting daemon process: "(98, 'Address already in use')"

Into:

  Error when starting daemon process: 'Socket-related error: Address
  already in use (errno=98)'

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>