Extract config server properties to Java bean

ConfigServerProperties is now used to store global properties
for the config server (like the path prefix and bootstrap flag)
under spring.cloud.config.server.* so git specific ones have
been pushed down to spring.cloud.config.server.git.* (similarly
for git->native).

At the same time introduce spring.cloud.config.server.defaultLabel
for the deafult git label (defaults to "master").

Fixes gh-28

spring-cloud-config-sample/src/test/java/sample/ApplicationTests.java

@@ -35,7 +35,7 @@ public class ApplicationTests {
 		ConfigurableApplicationContext context = SpringApplication.run(
 				org.springframework.cloud.config.server.ConfigServerApplication.class,
 				"--server.port=" + configPort, "--spring.config.name=server",
-				"--spring.cloud.config.server.uri=" + repo);
+				"--spring.cloud.config.server.git.uri=" + repo);
 		configPort = ((EmbeddedWebApplicationContext) context)
 				.getEmbeddedServletContainer().getPort();
 		System.setProperty("config.port", "" + configPort);

spring-cloud-config-sample/src/test/resources/server.yml

@@ -4,7 +4,8 @@ spring:
   cloud:
     config:
       server:
-        basedir: target/config
+        git:
+          basedir: target/config
   application:
     name: configserver
   jmx: