Challenges needed

[20jam]

We have the resources neccesry to create challenges. Challenges are great way to test what we have learned and do the actual coding part.

We should:

1. have a dir for challenges
2. Have a readme in challenges dir, with each challenge having a description and step by step guide (such as create a abstract class, create an abstract method, create setters and getter to get value x). Solution to these challenges should be kept inside challenges dir.

In readme challenges will be ordered by number from easy to hard, hard for integrating multiple concepts and making real decision.