in csv export sheet, update data column names

[stripathy]

Need to add a column to indicate that val_err is diff from val_sem

Based on @Justas's comment:

If you look at the summary spreadsheet here: http://neuroelectro.org/static/src/article_ephys_metadata_curated.csv, you'll see 6 terms per ephys property, for example for rmp: (rmp rmp_raw rmp_err rmp_n rmp_sd rmp_note). The n term is provided by the authors and the sd term is converted from the standard error (err) term provided by the authors.