Show-stoppers:

- Add a context menu to trigger actions

Not-quite show-stoppers:

- If the developer tries to upload a version that has already be marked
  as a previous version, ask her loudly if she is sure.

- The actions should be editable by keyboard shortcuts.  Likewise,
  "Escape" should exit, asking if the user is sure when actions where
  selected but not launched.

- The list of plugins included in the file should be shown, too.  We can
  use fiji.User_Plugins' parsePluginsConfig() method, probably after
  wrapping it into a public method that takes a String parameter
  containing the .jar file's path.

- make the list sortable by clicking on the column titles (second click
  sorts descending).
