Score/count processing sometimes hangs

[afrubin]

When uploading a dataset yesterday, I noticed that the page didn't progress past the "Scores and/or counts are being processed. Refresh this page in a few minutes to check on their status." step for some time. I edited the score set and re-uploaded the file, and then it progressed very quickly.

I'm not sure what's causing this intermittent behavior under the hood as I didn't see any output in the monitoring channel, but maybe as a stopgap we could add something to that error message that instructs users to try uploading the score table again if it doesn't progress after an hour or so.

[bencap]

Likely caused by something similar to #308, which should enable these score sets to get marked as failed.