Replace convict with configuration as parameters

[wkillerud]

Related #484

We should not have a dependency on convict inside the service. When running with npx it should take its parameters as arguments or as environment variables.

We're seeing some weirdness in the API after #577. We're making a logger instance and would like to access the name and loglevel configured locally in our Eik server, but there's a catch 22 where we can't get to service.config to read them. We then duplicate some convict stuff locally and it just gets a bit messy.

This would be a breaking change.