Move 'samples' into 'tests' folder

Some of the samples are more like pure integratiuon tests (I wouldn't
use them to copy code into a real app). So I put them with the other
"test" projects.

tests/samples-messaging-stream/src/main/java/com/example/DeleteSink.java

@@ -0,0 +1,32 @@
+/*
+ *  Copyright 2013-2016 the 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 com.example;
+
+import org.springframework.cloud.stream.annotation.Input;
+import org.springframework.cloud.stream.messaging.Sink;
+import org.springframework.messaging.SubscribableChannel;
+
+/**
+ * @author Marcin Grzejszczak
+ */
+interface DeleteSink extends Sink {
+
+	static String INPUT = "delete";
+
+	@Input(DeleteSink.INPUT)
+	SubscribableChannel delete();
+}