Add vagrant vbguest plugin to ensure matching guest additions

Vagrantfile

@@ -1,12 +1,19 @@
 # -*- mode: ruby -*-
 # vi: set ft=ruby :
 
+unless Vagrant.has_plugin?("vagrant-vbguest")
+  raise "Please install the vagrant-vbguest plugin by running `vagrant plugin install vagrant-vbguest`"
+end
+
 Vagrant.configure(2) do |config|
   # TODO: Switch back to the official box once it is released
   config.vm.box = 'opencraft/xenial64'
   config.vm.synced_folder '.', '/vagrant', disabled: true
   config.vm.synced_folder '.', '/home/vagrant/opencraft'
 
+  config.vbguest.auto_update = true
+  config.vbguest.auto_reboot = true
+
   config.vm.network 'forwarded_port', guest: 2001, host: 2001
   config.vm.network 'forwarded_port', guest: 5000, host: 5000
   config.vm.network 'forwarded_port', guest: 8888, host: 8888