fix siac units
fix siac units

`siac host -v` has been displaying 'Weeks' as the unit for 'windowsize',
but 'Hours' is the correct human-friendly value. The window size is now
displayed in hours.

`siac host config collateral` had been setting the value incorrectly,
converting using 'Bytes per Terabyte' instead of 'Bytes per terabyte
month'. The correct conversion is now used.

`siac host config -v` has displaying 'int' as the unit for
'maxdownloadbatchsize' and 'maxrevisebatchsize', but the unit is
actually bytes. This has been fixed as well.

mtlynch/Sia,ericflo/Sia,MrStrong/Sia,mnsl/Sia,NebulousLabs/Sia,mharkus/Sia,MrStrong/Sia,ericflo/Sia,ChrisSchinnerl/Sia,rivine/rivine,ChrisSchinnerl/Sia,mharkus/Sia,rivine/rivine,NebulousLabs/Sia,mnsl/Sia,mtlynch/Sia