Don't delegate to bulkhead, it might be nil

[dalehamel]

What

Prevent a nil pointer dereference if attempting to read the name (or any other attribute delegated to bulkhead) of a protected resource without a bulkhead.

Why

Since bulkheads are now optional, we shouldn't delegate anything explicitly to them, as this can result in a nil pointer dereference.

How

The name is attempted to be read from the bulkhead first, falling back to the circuit breaker. If neither works, it will be nil, but it won't cause an exception to be raised from a nil pointer dereference.

Every other attribute has a safe accessor method defined, which will return a default value (same as for an unprotected resource) if there is no bulkhead.

[dalehamel]

We might just want "allow_nil" here, not sure what the best behavior is.

[dalehamel]

Yeah, I think we should consider just doing allow_nil. This is definitely an error, I don't think we should mock every call.

@sirupsen looks like allow_nil is a rails thing, if we are just using forwardable we might need to manually delegate things to make them safe when the delegate is nil.