Operator shelf edit form (bug 1074431)

r? @ngokevin @cvan @spasovski 
This is a widget I janked from transonic that lets you select one or multiple apps, depending on what's appropriate. `.apps` signifies that we're using that widget, `.apps-multiple` that we want more than one app.

In the future we'll pull this out to be its own bower thing, so I left it as is for now to make the upgrade path smoother when that happens.