Clear rounding and citation_id_list from session data when starting over.
Fixed bug in get_upload_citations: @session[:citation] is the citation
id, not a citation object, so don't try to get the id using
@session[:citation].id.
In lookup_and_add_ids, handle the case where we need to look up a
treatment id but the citation was specified globally rather than
per-row in the CSV file.
Check that the session[:global_values] hash exists before trying to lookup data in it.