DBLogger sample

[aleks-f]

• create a Util::ServerApplication-based DBLogger sample in Poco::Data which:
  • connects to a database
  • logging thread produces some logs via SQLChannel in store-and-forward mode
  • forwarding thread:
    • monitors the directory where files with *.sql extension (containing SQL inserts statements) are saved by SQLChannel in store-and-forward mode
    • executes the queries in the *.sql files
      • in case of success, deletes the *.sql file
      • in case of error, renames the offending file from *.sql to *.err
    • any files with extension different from *.sql are ignored
  • use sqlite db for the sample (like other Poco::Data samples)