Allow adding new data files to existing data sets.
Fixed syntax error.
Set modification_time field for datafiles in data sets
appearing in feed if they don't already have a modification_time set.
Changing variable naming from lower camel-case to underscore-separated.
Merge branch 'cvl-emailtask-3.0beta' into cvl-dev

Conflicts:
	atom_ingest.py
Added note about test settings for tests to pass