Improve formatting of sizes in web view

[jwodder]

Currently, sizes of assets, versions, etc. are displayed in the web view as just plain integers. The display could be improved in either of the following ways:

• Add spaces or commas as thousands separators (and probably also right-align the numbers)
• Format as a number of KiB/MiB/GiB
  • Tera has a filesizeformat filter for doing this, though it seems to use ambiguous "MB"-style abbreviations

[jwodder]

@yarikoptic Do you have a preference about how to do this? Personally, I'd prefer just showing the full numbers with spaces as thousands separators, but a lot of people seem to like "12.3 MiB"-style displays.

[yarikoptic]

I got used to the ones we have on https://datasets.datalad.org/ , e.g. 62.8 GB. So overall preference -- "humanized". I rarely see *iB notation but ok with it as well ;-)