Setting invalid config value error when setting right valuse

[matthewcooper]

Setting invalid config values gets loaded into the memory version of the config. And then error when setting the right values.

1. Set hcs_interval to below 500
2. Error setting hcs_interval (correct error)
3. Set hcs_interval to 1000
4. Error setting hcs_interval (incorrect error)
5. restart PulseHA
6. Set hcs_interval to 1000
7. No error

PS also can you log the error thrown in config.go::Validate() as they are lost on the way out.