fix: Set Bento box version to last working version

The latest version of the Bento box caused the file sharing
to break, so fix the version to the last known working version.
This can be updated to a later version, once it has been fully
tested.

vagrant/Vagrantfile

@@ -3,6 +3,7 @@
 
 Vagrant.configure("2") do |config|
   config.vm.box = "bento/ubuntu-16.04-i386"
+  config.vm.box_version = "= 2.3.5"
   config.vm.network "forwarded_port", guest: 8000, host: 8000, host_ip: "127.0.0.1"
   config.vm.network "forwarded_port", guest: 8080, host: 8080, host_ip: "127.0.0.1"
   config.vm.network "forwarded_port", guest: 5000, host: 5000, host_ip: "127.0.0.1"