Output needs to be filtered to only contain one period

[Jday7879]

The output of selective_editing_contributor_output needs to only contain one date refered to as the "previous_period".
Wait for the question code to be merged before making this change as it will be easier to just use same syntax and code :)

Also need to update the output file names, but we do not know what names they are wanting at the moment. Wait for this info and do it all in one PR

monthly-business-survey-results/mbs_results/selective_editing_contributer_output.py

Line 55 in 0c0b407

return selective_editing_contributer_output