Logging `BedrockError.cause` needs to be improved

[mattcollier]

bedrock/lib/util.js

Lines 80 to 82 in eaac0b9

	if(err.cause && !_isErrorPublic(err.cause)) {
	object.cause = null;
	}

This code assumes that every cause would be a BedrockError that would be explicitly marked as public.

It is not common practice to wrap every error that might be included in a BedrockError in another BedrockError.

I think the practical solution here is to say that the cause should be logged if the outer BedrockError is marked as public.

This of course could mean that a cause leaks data that should not be exposed in logs. However, the current state of affairs makes it impossible to debug applications issues in deployments.