Added TaskNameResolver and related implementation

TaskNameResolver allows the ability to customize how a task is named.
During normal use cases, the provided SimpleTaskNameResolver should
suffice.

resolves spring-cloud/spring-cloud-task#54

spring-cloud-task-samples/timestamp/src/main/java/org/springframework/cloud/task/timestamp/TaskApplication.java

@@ -45,7 +45,7 @@ public class TaskApplication {
 	}
 
 	public static void main(String[] args) {
-		SpringApplication.run(TaskApplication.class);
+		SpringApplication.run(TaskApplication.class, args);
 	}
 
 	/**