Fix vagrant hang due to DNS resolver issue

Vagrantfile.snippet

#
# ... Other configs
#
config.vm.network :private_network, ip: "33.33.33.10"

# In certain cases, vagrant will hang for a long time and then
# error out. For some reason that I haven't bothered looking in
# to, I have to explicitly turn on the the vbox dns resolver.
#
config.vm.provider :virtualbox do |vb|
  vb.customize ["modifyvm", :id, "--natdnshostresolver1", "on"]
end

#
# ... Other configs
#