Update provision.py and Vagrantfile to support VMWare.

This adds support for using VMWare Fusion as the Vagrant provider,
which has better performance than Virtualbox at the price of being
nonfree (in all senses of the term).

We haven't done solid benchmarking as to how much faster it is than
the Virtualbox provider.

Vagrantfile

@@ -70,6 +70,12 @@ Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
     vb.cpus = 2
   end
 
+  config.vm.provider "vmware_fusion" do |vb, override|
+    override.vm.box = "puphpet/ubuntu1404-x64"
+    vb.vmx["memsize"] = "2048"
+    vb.vmx["numvcpus"] = "2"
+  end
+
 $provision_script = <<SCRIPT
 set -x
 set -e