Update hook for sv list #2033

Converts image boxes to use files instead of nodes.  All boxes get the displays updated to use the corresponding view mode.  Node boxes get their plugin keys updated, but I'm not actually sure we'll need that long term.

I'm not positive about any of the view modes for images because we haven't written them yet.  I just updated the options and hoped for the best.  We can fix them as the view modes become available.
SV list should return before rendering if empty #2033
SV list renamed 'full content' to 'entire post' #2033

This is what we called it in the previous list.  No need for the change, even if full content is the view mode's actual label.
Gave sv list fieldsets #2033

Now that there's an element for @dancabral to grab it should be possible to rearrange some of the selects in sv list.

Also took this time to rewrite some of the code I started with.
Fixed sv list box bug #2033

New LOP and LOF boxes weren't being added to the widgets list on the layouts page.  This is because their $box->new property was never set.  It wasn't set because I had my own __construct() method and forgot to call parent::__construct().
Merge pull request #4630 from openscholar/2033-sv_refactor

2033 sv refactor