Unmatched files during scan yields NoneType in ingests list

[gisjedi]

If a Scan runs that detects files that then do not match ANY rule, None is returned by ingest.scan.scanners.scanner._process_ingest by design. Not by design, is the fact that ingest.scan.scanners.scanner._process_scanned adds these None returned values from _ingest_file to the ingests list. (https://github.com/ngageoint/scale/blob/master/scale/ingest/scan/scanners/scanner.py#L172) We need to actually check for None before adding these.