Refactoring samples

Restructuring the samples repository
Add more docker support
Add acceptance tests for the apps
Adding sensor average processor sample
Remove aggregate samples

source-samples/jdbc-source/README.adoc

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+Spring Cloud Stream Source Sample
+==================================
+
+## What is this app?
+
+This is a Spring Boot application that is a Spring Cloud Stream sample source app that polls a JDBC Source.
+This application specifically uses MySQL (MariaDB flavor) to query a particular table and output the contents of the table every n seconds(details below).
+In reality, you probably want to use the out of the box variant of JDBC source from https://github.com/spring-cloud-stream-app-starters/jdbc which is more advanced.
+Refer to the documentation of Spring Cloud Stream app starters for the latest links for generated apps for specific binders.
+
+## What is the default binder used in this app?
+
+The default binder used in this app is Kafka.
+If you need to change it to Rabbitmq, change the appropriate dependency in the maven pom.xml
+
+## Requirements
+
+To run this sample, you will need to have installed:
+
+* Java 8 or Above
+
+This sample Source uses Spring Integration to poll a JDBC source and requires a Poller.
+The app provides a basic trigger based Poller which polls every 5 seconds by default.
+You can change the polling frequency by using the property `jdbc.triggerDelay`.
+
+# Additional properties used in this app
+
+Refer to the `application.yml` for the defaults used for the following properties.
+
+`jdbc.query` - SQL used to query the database.
+`jdbc.update` - SQL used to skip records already seen (details below)
+
+## Running the application using Kafka binder
+
+The following instructions assume that you are running Kafka and MySql as Docker images.
+
+* Go to the application root
+* `docker-compose up -d`
+
+* Open another terminal
+* Ensure that you have the `mysql` CLI tool installed and then use this command:
+`mysql -u root -p  -h 127.0.0.1 -P 3306 sample_mysql_db`
+
+`sample_mysql_db` is the name of the database created by the mysql that is running in the docker container.
+
+* Go back to the other terminal (root of this sample app `source`)
+* `./mvnw clean package`
+
+When you start the app, it will insert some test data into the database.
+See the method annotated with`PostConstruct` in the application.
+
+* `java -jar target/sample-jdbc-source-0.0.1-SNAPSHOT.jar`
+
+The application has a convenient test sink that consumes from the same destination where the source sends data.
+This test sink will output the data on the console.
+Alternatively, you can connect to the topic using a Kafka console consumer and watch the output.
+
+## Changing the default behavior of the app.
+
+If you want to query the app every second now, and ignore any records that you already saw, there are provisions for that in this sample.
+
+* Stop the app
+* `java -jar target/sample-jdbc-source-0.0.1-SNAPSHOT.jar --jdbc.triggerDelay=1 --jdbc.query="select id, name, tag from test where tag is NULL order by id" --jdbc.update="update test set tag='1' where id in (:id)"`
+
+* Now go to your MySQL CLI: Insert some data
+
+`insert into test values (20, 'Bob', NULL);`
+`insert into test values (22, 'Bob', NULL);`
+
+Watch the data appear on the application console.
+
+Once you are done testing, stop Kafka running in the docker container: `docker-compose down`
+
+## Running the application using Rabbit binder
+
+All the instructions above apply here also, but instead of running the default `docker-compose.yml`, use the command below to start a Rabbitmq cluser.
+
+* `docker-compose -f docker-compose-rabbit.yml up -d`
+
+* `./mvnw clean package -P rabbit-binder`
+
+* `java -jar target/sample-jdbc-source-0.0.1-SNAPSHOT.jar`
+
+Once you are done testing: `docker-compose -f docker-compose-rabbit.yml down`