- some more code comments
- fixed bug in the expire function, cleanup all_versions array during run. Otherwise it could happen that we try to delete already deleted versions

some more clean-up, isVersioned() is no longer needed; rename hook fixed if a complete folder gets renamed

Fall back to default log file if logfile config file not found

Fall back to default log file if logfile config file not found, suppress writing errors, fixes issue #826

Change post_write hook to write for files_versions app

wrap hooks into a try, catch to prevent a faulty app from crashing the request

use json when deleting multiply files instead of using ; as delimiter