Add explicit docs for eureka.hostname in secure app registration

Eureka supports native placeholders, but Spring can also be used.
Added some docs to show how more explicitly.

See gh-761

docs/src/main/asciidoc/spring-cloud-netflix.adoc

@@ -105,9 +105,26 @@ respectively. This will make Eureka publish instance information
 showing an explicit preference for secure communication. The Spring
 Cloud `DiscoveryClient` will always return an `https://...` URI for a
 service configured this way, and the Eureka (native) instance
-information will have a secure health check URL. Because of the way
+information will have a secure health check URL. 
+
+Because of the way
 Eureka works internally, it will still publish a non-secure URL for
 status and home page unless you also override those explicitly.
+You can use placeholders to configure the eureka instance urls,
+e.g.
+
+.application.yml
+----
+eureka:
+  instance:
+    statusPageUrl: https://${eureka.hostname}/info
+    healthCheckUrl: https://${eureka.hostname}/health
+    homePageUrl: https://${eureka.hostname}/
+----
+
+(Note that `${eureka.hostname}` is a native placeholder only available
+in later versions of Eureka. You could achieve the same thing with
+Spring placeholders as well, e.g. using `${eureka.instance.hostName}`.)
 
 NOTE: If your app is running behind a proxy, and the SSL termination
 is in the proxy (e.g. if you run in Cloud Foundry or other platforms

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/InstanceInfoFactory.java

@@ -18,12 +18,12 @@ package org.springframework.cloud.netflix.eureka;
 
 import java.util.Map;
 
-import lombok.extern.apachecommons.CommonsLog;
-
 import com.netflix.appinfo.EurekaInstanceConfig;
 import com.netflix.appinfo.InstanceInfo;
 import com.netflix.appinfo.LeaseInfo;
 
+import lombok.extern.apachecommons.CommonsLog;
+
 /**
  * See com.netflix.appinfo.providers.EurekaConfigBasedInstanceInfoProvider
  * @author Spencer Gibb
@@ -40,13 +40,15 @@ public class InstanceInfoFactory {
 		// server
 		InstanceInfo.Builder builder = InstanceInfo.Builder.newBuilder();
 
-		builder.setNamespace(config.getNamespace())
-				.setAppName(config.getAppname())
+		String namespace = config.getNamespace();
+		if (!namespace.endsWith(".")) {
+			namespace = namespace + ".";
+		}
+		builder.setNamespace(namespace).setAppName(config.getAppname())
 				.setInstanceId(config.getInstanceId())
 				.setAppGroupName(config.getAppGroupName())
 				.setDataCenterInfo(config.getDataCenterInfo())
-				.setIPAddr(config.getIpAddress())
-				.setHostName(config.getHostName(false))
+				.setIPAddr(config.getIpAddress()).setHostName(config.getHostName(false))
 				.setPort(config.getNonSecurePort())
 				.enablePort(InstanceInfo.PortType.UNSECURE,
 						config.isNonSecurePortEnabled())