Task #8291: Use store module to save results and queues persistent. Removed reporting. We'll have to use store + reporting for that as well

Task #8291: fix: creation_date for file_info. query leastRecentlyVisitedDirectory with before_timestamp.

Task #8291 added insertFileInfo method and modified subDirectories and rootDirectories method. Adapted tests.

Task #8291 added store module with LTAStorageDb class which can store file- and directory info in sqlite3 database

Task #8291 made lib and bin dir. added ltastorageoverviewscraper executable wrapper script to bin. added copyrights.

Task #8291: refactored get_srm.py to run srmls commands in parallel, distributed over the storage sites, and dynamically scaling with system load. 
Results are gathered in a tree.
Intermediate results and queues are pickled, which is way too slow.

Task #8291 made initial directory structure for lta storage overview package. Added original get_srm.py script by Adriaan as start