Determine deployable app version dynamically

The deployer now checks its own version and uses that to set
up the app versions via "launcher.version" on the command line.

Closes gh-16

spring-cloud-launcher/spring-cloud-launcher-deployer/src/main/java/org/springframework/cloud/launcher/deployer/DeployerThread.java

@@ -62,6 +62,8 @@ public class DeployerThread extends Thread {
 
 	private static final Logger logger = LoggerFactory.getLogger(DeployerThread.class);
 
+	private static final String DEFAULT_VERSION = "1.2.0.BUILD-SNAPSHOT";
+
 	private Map<String, DeploymentState> deployed = new ConcurrentHashMap<>();
 
 	private String[] args;
@@ -169,12 +171,17 @@ public class DeployerThread extends Thread {
 		return null;
 	}
 
+	private String getVersion() {
+		Package pkg = DeployerThread.class.getPackage();
+		return (pkg != null ? pkg.getImplementationVersion() : DEFAULT_VERSION);
+	}
+
 	private void launch() {
 
 		final ConfigurableApplicationContext context = new SpringApplicationBuilder(
 				PropertyPlaceholderAutoConfiguration.class, DeployerConfiguration.class)
 						.web(false).properties("spring.config.name=cloud",
-								"banner.location=launcher-banner.txt")
+								"banner.location=launcher-banner.txt", "launcher.version="+getVersion())
 						.run(this.args);
 
 		final AppDeployer deployer = context.getBean(AppDeployer.class);

spring-cloud-launcher/spring-cloud-launcher-deployer/src/main/resources/cloud.yml

@@ -1,6 +1,6 @@
 dt:
   pre: maven://org.springframework.cloud.launcher:spring-cloud-launcher-
-  ver: 1.2.0.BUILD-SNAPSHOT
+  ver: ${launcher.version}
 spring:
   cloud:
     launcher: