every class should extend at least the object class
remove unused package. improve code style at some places.
add docu
remove unused methods
move class comment into class
remove unused import and delete empty lines
launch correct backup function at start
document the for…else case
try to implement the actual download of updated files from dropbox. also remove deleted files
move load_state and save_state to the right place at the top.

have these methods at the top together with init as they all read
backup or access_key states from config files.
also cleanup search cache when cleaning backups
fix some errors to make it actually download files