* On OSX, install a launcher plist file, to run the assistant on login,
  and a `git-annex-webapp.command` file in the desktop. This is not tested
  yet.
* Made the webapp display alerts when the inotify/kqueue layer has a
  warning message.
* Handle any crashes of each of the 15 or so named threads by displaying
  an alert. (Of course, this should never happen.)