Minor tweaks to download code
 

Just a couple fixes for the download code. I'm not entirely convinced that the
values hard coded in patch 2/2 are appropriate, so I'll say that its up for
discussion. I know that we have folks who insist on using dial-up, so we need
to be aware of this as well. Based on the source of curl, it seems to be a
comparison of the average speed over the life of the transfer against the low
speed limit, so this would actually be elongated on larger transfers.
Regardless, this should address bug reports such as FS#23690 and FS#15369.

dave