Major work done:
    - Added ActivityCommunicator and FragmentCommunicator interfaces and implemented them to work
    - Added Lesson class: data holder for a single lesson
    - Added a custom nicer TypeFace for the ListView
    - Implemented parsing of ClassData.json , both options are working (internet/assets)  into TimeTable HashMap<String, Lesson>
    - Added function UpdateHashTable that sets a list of hashes for currently chosen group and stores it in ClassHashes List
    - Added function UpdateList that takes currently needed lessons according to ClassHashes list from TimeTable HashMap
    - Added function loadJSONFromAssets that takes a filename as input and returns JSON formatted String suitable for JSONObject creation
    - Added ClassListArrayAdapter and ClassView, both are working, the List with classes for current group is showing with right layout