NOTEPAD-8 UPDATE A NOTE
- made list of notes clickable
- opens input screen and show the NoteFragment with the respective title
  and description of the entry on a click
- detects if note is edited
- updates entry in the database
- checks if edited title allready exists
- checks if title or description is empty after editing
- created showCreate() and showUpdateNote() method in main activity
- fixed variable name in NoteInputFragment