Move from @Value for properties defaults to allow relaxed binding for defaults

[spencergibb]

@value("${spring.application.name:unknown}")

[wind57]

this is present on :

	/** The service name of the local instance. */
	@Value("${spring.application.name:unknown}")
	private String serviceName = "unknown";

a field in org.springframework.cloud.kubernetes.commons.discovery.KubernetesDiscoveryProperties.java.

The only usage of the getter of that property is in org.springframework.cloud.kubernetes.fabric8.registry.KubernetesRegistration. That package should be removed entirely, but that is only possible in 2.x, i.e.: on a major release.

I propose to make this change in a PR and keep it open until that time comes. This way, it will not go out of site; unless you see a problem to keep a PR open for some time.