Three minor code enhancements (#1014)

core/src/main/java/com/taobao/arthas/core/command/monitor200/ThreadCommand.java

@@ -53,7 +53,7 @@ public class ThreadCommand extends AnnotatedCommand {
     private String state;
 
     {
-        states = new HashSet<String>(8);
+        states = new HashSet<String>(State.values().length);
         for (State state : State.values()) {
             states.add(state.name());
         }

tunnel-server/src/main/resources/application.properties

@@ -1,8 +1,8 @@
 
-
+# arthas http port
 arthas.server.port=7777
-
+# for all endpoints
 management.endpoints.web.exposure.include=*
 
-
+# default user name
 spring.security.user.name=arthas