The ability to link to an account by using an archive file is
introduced in the wizard dialog. A button is added to chose an archive
file instead of downloading it from the DHT.

Change-Id: I3129ee1c9f1fd2fb69845fdbeb4d7858e81af366
Reviewed-by: Kateryna Kostiuk <kateryna.kostiuk@savoirfairelinux.com>