Add EventHubClientFacotry interface to create client by event hub name

spring-cloud-azure-eventhub/src/main/java/eventhub/core/EventHubClientFactory.java

@@ -0,0 +1,24 @@
+/*
+ *  Copyright 2017-2018 original author or authors.
+ *
+ *  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 eventhub.core;
+
+import com.microsoft.azure.eventhubs.EventHubClient;
+
+public interface EventHubClientFactory {
+
+    EventHubClient createEventHubClient(String eventHubName);
+}