change default sorts in table browsing (for search too)

as per https://www.reddit.com/r/haskell/comments/85jh04/has_the_hackage_website_been_updated/dvyh6ya/

> There is really no point at all in sorting by:
> 
> name
> description
> tags
> maintainer
>
> But sorting by these is nice:
> 
> downloads
> rating
> last upload

So we should pick a good one for default sort, and also arguably remove the sorting on useless cols.