Refactor Config.java

[Tiihott]

Description
Refactor Config.java to be more OOP.

• Make a common configuration class that holds all the properties.
• Replace typical getter structure with printers.
• Print property values based on key.
• Allow printing the kafka configuration properties separately for the consumer.
• Implement validation of the configuration properties in a way that it is not in the constructor.

[Tiihott]

Solved in beta branch PR #41

Additional changes were requested to the refactoring in the PR.

• Split the properties of ingress library (kafka) to different file from egress library(hdfs) and leave strictly application configuration to the main application.properties file.
• Use separate object for each of the properties.

[Tiihott]

Implemented the additional changes to PR #41.