Add testapp and remove duplicate text from README. (#1518)

Closes #1517.

spring-data-testapp/src/main/java/com/example/demo/DemoApplication.java

@@ -0,0 +1,19 @@
+package com.example.demo;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+
+@SpringBootApplication
+public class DemoApplication {
+
+	char a = '\u00A0';
+	public static void main(String[] args) {
+		new SpringApplicationBuilder ( DemoApplication.class)
+				.properties("spring.main.allow-bean-definition-overriding=true")
+				.build()
+				.run(args);
+	}
+
+
+}