Refactored config file resource loading to make it easier to load config files from class path when embedding.

broker/src/main/java/io/moquette/server/config/IResourceLoader.java

@@ -0,0 +1,19 @@
+package io.moquette.server.config;
+
+import java.io.Reader;
+
+public interface IResourceLoader {
+
+    Reader loadDefaultResource();
+
+    Reader loadResource(String relativePath);
+
+    String getName();
+
+    class ResourceIsDirectoryException extends RuntimeException {
+        public ResourceIsDirectoryException(String message) {
+            super(message);
+        }
+    }
+
+}