Sorting datasets by "Size" in Admin Site doesn't sort perfectly

[bryanmgee]

Regardless of whether you sort 'ascending' or 'descending,' the Admin Site doesn't always sort perfectly when using the Size column. Some examples:

[ryscher]

To be considered with #3200

[ahamelers]

I think there might be a mismatch between the size depicted (the size of the current version) and the size used in the db calculation & sorting (maybe the size of all versions?)

In the new Admin dashboard (datadryad/dryad-app#1703) both definitely use the same number.