BLS - QCEW File name assumption causes failure

[ethervoid]

@joofeloof reported that in some cases we can have an error trying to download the BLS - QCEW dataset.

You've implicitly assumed one would only extract full year such that q1-q4 would be contained in the input_csv file name. Currently, 2016 is named as q1-q3 so the load fails due to input_csv returned invalid file. I don't know if when 2017.1 is available they will name it q1-q1 (seems unlikely) but I don't want to make the assumption as of yet.

He did a PR #140 but we need to polish it to fit in our requirements.