Dashboard: use IEC prefixes for pipeline disk space readout.
Dashboard: use IEC prefixes for pipeline disk space readout.

GNU df insists on reporting GB as 2^20 bytes instead of 10^9 bytes.
(It'll use SI prefixes with -H, but that's not default behavior.) It's
easier to harmonize ArchiveBot's dashboard than it is to change df.

JesseWeinstein/ArchiveBot,ArchiveTeam/ArchiveBot,emijrp/ArchiveBot,Frogging101/ArchiveBot,Frogging101/ArchiveBot,emijrp/ArchiveBot,falconkirtaran/ArchiveBot,JesseWeinstein/ArchiveBot,JesseWeinstein/ArchiveBot,Frogging101/ArchiveBot,ArchiveTeam/ArchiveBot,emijrp/ArchiveBot,falconkirtaran/ArchiveBot,falconkirtaran/ArchiveBot,falconkirtaran/ArchiveBot,Asparagirl/ArchiveBot,ArchiveTeam/ArchiveBot,ArchiveTeam/ArchiveBot,Asparagirl/ArchiveBot,JesseWeinstein/ArchiveBot,Asparagirl/ArchiveBot,Asparagirl/ArchiveBot,emijrp/ArchiveBot,Frogging101/ArchiveBot,JesseWeinstein/ArchiveBot,Asparagirl/ArchiveBot,emijrp/ArchiveBot,Frogging101/ArchiveBot,ArchiveTeam/ArchiveBot,falconkirtaran/ArchiveBot