Add ac_monitor.py script providing real-time monitoring of an ACQt production.

In future each worker node creates a tar archive containing the log file, the job log file and the ACQt files, once the job finishes.
This file is then copied into a "ToBeValidated" directory, which is monitored (w/o polling, by linux-FAM hooks) by ac_monitor.py for new files.

For each new .tar file in the "ToBeBalidated" directory ac_monitor.py does:
- Extract job information from .tar file name (ACQt Version, Data set (ISS/BT/MC), and run number + first event in run)
- Try to untar the archive into a temporary directory
- Parse log file and job log file, extract following data:
  - number of events in AMS ROOT file, in ACQt PWT/SAA/OTH streams, in the user-defined streams (eg. ac2ecal, etc..)
  - duration of production job
  - file sizes
  - number of events per chunk, number of chunks per file, etc.
  ...
- Run acroot_dump to extract Git SHA1 of ACqt production for every file (PWT.acqt file, etc..)
- Run acroot_check to validate all chunks.
- Write all these information into a SQLite3 Database, which can be used to provide real-time production monitoring with web based visualization.

The idea is to have one database file per production "flavour", eg. "590_pass4.db" covering the ACQt 5.9.0 pass4 production, with two tables.
One table "AMSROOTProductionStatus" should contain all information about the AMS ROOT files (file size, number of events, check sum, ...)
The other table "ACQtProductionStatus" is filled by ac_monitor.py during the running ACQt production.

If partial steps failed, not all infromation will be available in each DB entry, but it contains as much information as possible.
If a job fails and has to be reprocessed, the previous entry in the database for that run is kept, and an "iteration" column is incremented by 1.
This way we can have multiple entries per run, to be able to cover the whole production history in that database.

TODO:
- Test with another else than pass4 (MC/BT/ac2ecal stream)
- Copy result to final location, once validation finished.
- ...