submit should nag if submission file is not a zip/gz/rar/7z (because upload BW is so low)

[smcinerney]

submit should warn if submission file is not a zip/gz/rar/7z. This can make the difference between 10min upload time vs 30sec. Due to the low upload bandwidth (< 1Mbps).

(Also this warning should be suppressable, for users who really insist on uploading a raw CSV file.)

Also, as to bandwidth, it would be nice to report file size, upload time and BW (Mbps) after upload. Then users could automatically figure out what times of day (UTC-8) are fast/slow.
Probably also useful to report which proxy, if any, was used, as that may affect things.