Preload owners in plugin lists

[mrclay]

Use something like: Elgg/Elgg#6731

[beck24]

closing this as it looks like that's something that should be in core and ultimately will end up being one day. I don't want to shoehorn in custom implementations that just have to be ripped out later when it's handled correctly by default.

[juho-jaakkola]

We can do this as soon as community has been updated to Elgg 1.10. We will however need to manually add the 'preload_entities' => true parameter. Therefore reopening.

See http://learn.elgg.org/en/1.x/guides/views.html#listing-entities