Spark Java Article BAEL-498 (#912)

* Initial Commit for Spark Java Article BAEL-498

* reverting main pom.xml and rollbacking accidental changes.

* Changes as per review:

1. Added UserService
2. Renamed UserStore to UserServiceMapImpl
3. Removed Empty spaces in User.java
4. Removed AppTest
5. Changes in SparkRestExample for using UserServiceMapImp instead of
UserStore static functions.

* Suggested changes in print messages.

* Changes as per comments on github... for PR:
https://github.com/eugenp/tutorials/pull/912

* Changes in editUser function as per guidance by Kevin.

* Clean up

* added 1.8 config for pom.xml

* Clean up.

* Removed junit dep.

* Added Application/json in response type.

spark-java/src/main/java/com/baeldung/sparkjava/StandardResponse.java

@@ -0,0 +1,47 @@
+package com.baeldung.sparkjava;
+
+import com.google.gson.JsonElement;
+
+public class StandardResponse {
+    private StatusResponse status;
+    private String message;
+    private JsonElement data;
+
+    public StandardResponse(StatusResponse status) {
+        this.status = status;
+    }
+
+    public StandardResponse(StatusResponse status, String message) {
+        this.status = status;
+        this.message = message;
+    }
+
+    public StandardResponse(StatusResponse status, JsonElement data) {
+        this.status = status;
+        this.data = data;
+    }
+
+    public StatusResponse getStatus() {
+        return status;
+    }
+
+    public void setStatus(StatusResponse status) {
+        this.status = status;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public JsonElement getData() {
+        return data;
+    }
+
+    public void setData(JsonElement data) {
+        this.data = data;
+    }
+}