Single logging framework should be enforced

[iluwatar]

As aligned in https://github.com/iluwatar/java-design-patterns/wiki/10.-Technology-selections we should use Slf4j API with Logback implementation as logging framework. However, some patterns are still using log4j. In this issue we migrate them to Logback.

[lauramurinova]

Hello, I would like to try and solve the issue.

[iluwatar]

Thanks @lauramurinova, go ahead

[lauramurinova]

Sorry eventually I cannot work on this.

[iluwatar]

Ok @lauramurinova and thanks for notifying