Split into multiple Files

- Each Class has each own file now, located in src/

- Dropbox was renamed to DropboxWrapper to make clear, that it is not a main file

- The main / controlling logic was encapsuled in the Dropper class

- The dropper.py file only initializes the Dropper object and calls simple functions on it.
	No crucial logic shall be in it

- Small "interface" improvements:
	- while initializing / scanning the Path output overwrites previous paths
	- Only downloaded files are displayed (No more "no need for Download")