ElasticMap: use vert.x event loop for requests & responses.

- fixes a deadlock trying to close the apache internal http client from request thread.

Author: Robin Duda

core/main/java/com/codingchili/core/Launcher.java

@@ -1,8 +1,6 @@
 package com.codingchili.core;
 
-import com.codingchili.core.configuration.exception.NoServicesConfiguredForBlock;
 import io.vertx.core.*;
-import org.apache.commons.jexl2.JexlEngine;
 
 import java.util.ArrayList;
 import java.util.List;

core/main/java/com/codingchili/core/context/ShutdownHook.java

@@ -18,8 +18,8 @@
  */
 public class ShutdownHook extends Thread {
     private static final Map<Vertx, ShutdownHook> contexts = new HashMap<>();
-    private SystemContext context;
-    private Logger logger;
+    private final SystemContext context;
+    private final Logger logger;
 
     /**
      * Registers a context for graceful shutdown as a JVM hook so that the context