Fix VB Guest Addition update error in Vagrant

Ever get problems with your Vagrant informing you that your Virtualbox Guest
Additions is of a different version than your Virtualbox version?

[default] The guest additions on this VM do not match the install version of
VirtualBox! This may cause things such as forwarded ports, shared
folders, and more to not work properly. If any of those things fail on
this machine, please update the guest additions and repackage the
box.

Guest Additions Version: 4.1.22
VirtualBox Version: 4.2.6

There’s a
fix!

# In your Vagrantfile root directory
$ vagrant plugin install vagrant-vbguest

Now, the latest version of guest additions will always be added after booting
up.