DatasetResult objects now have property 'thredds_filecount' which is
the value of 'number_of_files' variable from the json reply
Add las_url property
Handle file records with missing checksums.
Merge branch 'pchengi-master' into devel
Renaming DatasetResult.thredds_filecount to DatasetResult.number_of_files
Merge remote-tracking branch 'upstream/devel'