Support re-run

[RobTranquillo]

actually the program is build to run one time. But its needed to run constantly (maybe by cron). Necessary to archive that is:
0) recognize if an old run is up and running actually, and give a warn.

1. make a scan over the downloaded sessions of the last year /or more)
2. re-download all sessions that have new/changed documents
3. download all complete new sessions