Add a ValidateLogConfigs function to config.go. (#664)
Add a ValidateLogConfigs function to config.go. (#664)

* Add a ValidateLogConfigs function to config.go.

This function is to validate a single-backend configuration.

daviddrysdale/certificate-transparency-go,google/certificate-transparency-go,google/certificate-transparency-go,daviddrysdale/certificate-transparency-go,daviddrysdale/certificate-transparency-go,google/certificate-transparency-go