#970 single logging framework should be enforced (#982)

* #496 Add pipeline module to parent pom ✨

* #496: Add main application class and test for pipeline

* #496: Checkstyle format and add log messages on pipeline stages 🎨

* #496: Fill readme sections of pipeline ✨

* #496: Javadocs and checkstyle formatting 🎨

* #496: Follow PMD checks and add more explanation as block comment on App.java

* #496: Apply requested PR changes by iluwatar 🎨

* #970: Replace log4j usage on commander pattern to Slf4j API 🎨

* #970: Replace log4j usage on dao pattern to Slf4j API 🎨

* #970: Replace log4j usage on data mapper pattern to Slf4j API 🎨

* #970: Remove log4j dependency on data transfer object pom 🔥

* #970: Replace log4j usage on module pattern to Slf4j API 🎨

* #970: Replace log4j usage on serverless pattern to Slf4j API 🎨

This also removes the aws log4j dependency

* #970: Remove unnecessary gitignore line for log4j.xml 🔥

* #970: Remove remaining remnants of log4j 🔥

* #970: Replace System.out logging with appropriate logging methods 🎨

* #970: Replace System.out method references to Logger::info 🎨

data-mapper/src/main/java/com/iluwatar/datamapper/App.java

@@ -22,9 +22,10 @@
  */
 package com.iluwatar.datamapper;
 
-import java.util.Optional;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-import org.apache.log4j.Logger;
+import java.util.Optional;
 
 /**
  * The Data Mapper (DM) is a layer of software that separates the in-memory objects from the
@@ -39,7 +40,7 @@ import org.apache.log4j.Logger;
  */
 public final class App {
 
-  private static Logger log = Logger.getLogger(App.class);
+  private static Logger log = LoggerFactory.getLogger(App.class);
   private static final String STUDENT_STRING = "App.main(), student : ";