downloads: improve logger messages

[missinglink]

the current log output when downloading TIGER files is very verbose and at the same time not super informative

info: [interpolation(TIGER)] Queuing 1 downloads
info: [interpolation(TIGER)] Downloading tl_2021_41051_addrfeat.zip
info: [interpolation(TIGER)] Queuing 1 downloads
info: [interpolation(TIGER)] Downloading tl_2021_41005_addrfeat.zip
info: [interpolation(TIGER)] Queuing 1 downloads
info: [interpolation(TIGER)] Downloading tl_2021_41071_addrfeat.zip
info: [interpolation(TIGER)] Queuing 1 downloads
info: [interpolation(TIGER)] Downloading tl_2021_41047_addrfeat.zip
info: [interpolation(TIGER)] Queuing 1 downloads
info: [interpolation(TIGER)] Downloading tl_2021_41053_addrfeat.zip
info: [interpolation(TIGER)] Queuing 1 downloads
info: [interpolation(TIGER)] Downloading tl_2021_53011_addrfeat.zip

this PR changes a few things:

• the 'Queuing 1 downloads' line is fairly redundant, I moved it to the debug log level
• the 'Downloading' and 'Downloaded' lines are swapped, so you get the 'downloaded' at the regular info log level
• a completion log line is printed as per other downloaders
• messages are lowercased (personal preference but IMO it looks better)