Allow additional header lines in bandwidth measurements documents

As commented by teor in: https://github.com/pastly/simple-bw-scanner/pull/112#issuecomment-385108911

get it backported to 0.2.9 and later. I think Tor should only warn if: an incomplete line contains a "bw=" key an incomplete line contains a "node_id=" key an incomplete line occurs after the first complete line

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information