Create Project with Sample Spring Shell Tests

Just like spring-shell/spring-shell-samples shows examples of Spring
Shell features, create a project with samples of Spring Shell unit,
functional and integration tests.

Issue: SHL-192
https://jira.spring.io/browse/SHL-192

spring-shell-test-samples/src/main/java/com/example/CalculatorApplication.java

@@ -0,0 +1,19 @@
+package com.example;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ *
+ * Main entry point for the illustrative Spring Shell Calculator application.
+ *
+ * @author Sualeh Fatehi
+ */
+@SpringBootApplication
+public class CalculatorApplication {
+
+	public static void main(final String[] args) {
+		SpringApplication.run(CalculatorApplication.class, args);
+	}
+
+}

spring-shell-test-samples/src/main/java/com/example/CalculatorCommands.java

@@ -0,0 +1,33 @@
+package com.example;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.shell.standard.ShellCommandGroup;
+import org.springframework.shell.standard.ShellComponent;
+import org.springframework.shell.standard.ShellMethod;
+
+/**
+ *
+ * Basic commands for the illustrative Spring Shell Calculator application.
+ *
+ * @author Sualeh Fatehi
+ */
+@ShellComponent
+@ShellCommandGroup("Calculator Commands")
+public class CalculatorCommands {
+
+	@Autowired
+	private CalculatorState state;
+
+	@ShellMethod(value = "Add two integers")
+	public int add(final int a, final int b) {
+		return a + b;
+	}
+
+	@ShellMethod(value = "Add an integer to the value in memory")
+	public int addToMemory(final int b) {
+		final int sum = state.getMemory() + b;
+		state.setMemory(sum);
+		return sum;
+	}
+
+}

spring-shell-test-samples/src/main/java/com/example/CalculatorState.java

@@ -0,0 +1,25 @@
+package com.example;
+
+/**
+ *
+ * Program state for the illustrative Spring Shell Calculator application.
+ *
+ * @author Sualeh Fatehi
+ */
+public class CalculatorState {
+
+	private int memory;
+
+	public void clear() {
+		memory = 0;
+	}
+
+	public int getMemory() {
+		return memory;
+	}
+
+	public void setMemory(final int memory) {
+		this.memory = memory;
+	}
+
+}