Add MultiUserChatManager

apply the Manager pattern to 'muc'. This prevents the user creating
multiple MultiUserChat instances for the same MUC.

Move the static method from MultiUserChat to MultiUserChatManager.

Also add AbstractNodeInformationProvider.

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/AbstractNodeInformationProvider.java

@@ -0,0 +1,47 @@
+/**
+ *
+ * Copyright © 2014 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.disco;
+
+import org.jivesoftware.smack.packet.PacketExtension;
+import org.jivesoftware.smackx.disco.packet.DiscoverInfo;
+import org.jivesoftware.smackx.disco.packet.DiscoverItems;
+
+import java.util.List;
+
+
+/**
+ * 
+ */
+public abstract class AbstractNodeInformationProvider implements NodeInformationProvider {
+
+    public List<DiscoverItems.Item> getNodeItems() {
+        return null;
+    }
+
+    public List<String> getNodeFeatures() {
+        return null;
+    }
+
+    public List<DiscoverInfo.Identity> getNodeIdentities() {
+        return null;
+    }
+
+    public List<PacketExtension> getNodePacketExtensions() {
+        return null;
+    }
+
+}