Implement testing for parsing

[Zoltan-Balazs]

To better ensure that the Class file is parsed correctly, testing must be implemented.

• As of the issue's opening, I have not figured out what testing library to use
• I need reproducible cases to check validity of Class file parsing
• Also need some sample files to parse (probably "Hello World", simple List application, etc.)

[Zoltan-Balazs]

Likely candidate for unit testing library is JUnit

[Zoltan-Balazs]

Testing library is a custom python script, that checks output of built-in Java command to running the program.