added test endpoint (#24)

Author: AlfredoMate

src/main/java/io/autoinvestor/ui/TestEndpoint/ControllerTest.java

@@ -0,0 +1,13 @@
+package io.autoinvestor.ui.TestEndpoint;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class ControllerTest {
+
+    @GetMapping("/testUser")
+    public String handler() {
+        return "Congrats. You reached the users service.";
+    }
+}