Remove most annoying UI "feature" of the new authority browse list interface

Remove most annoying UI "feature" of the new authority browse list interface

When I added the new authority browse list interface, I used dojo.xhrGet()
to retrieve records from the authority browse backend - but because I didn't
specify sync:true, when you first right-clicked on a subfield, the function
would return immediately and default to showing the context menu. You would
then need to click two more times to show the authority list.

Now you get it on your first right-click, as it should be.

git-svn-id: svn://svn.open-ils.org/ILS/trunk@17910 dcc99617-32d9-48b4-a31d-7c20da2025e4