admin-ajax timeout when searching for images to bulk convert

When using the bulk convert option, the server times out while waiting to retrieve the list of images to convert.

I was able to workaround this by manually changing the timeout in lib/options/js/bulk-convert.js

timeout: 30000

to:

timeout: 60000

Given that this operation can take a long time, it might be worthwhile to update the default timeout to something at least 60000 if not 120000