The following settings shouldn't exist: max_tries, timeout
$ vagrant up
して
The following settings shouldn't exist: max_tries, timeout
って出てきたらVagrantfileの様式が古いので
config.ssh.max_tries = 40
config.ssh.timeout = 120
この2行消すととりあえず動く
https://github.com/berkshelf/berkshelf/commit/2d0f1546409099c4d62aee8ce5d98ce99ae26f01