Add explicit sync folder option to Vagrantfile (#1278)

- Without the explicit sync folder ownership option, Vagrant 2.2.0 fails to create the "vendor/" directory when when running `vagrant up` the first time.

Vagrantfile

@@ -27,6 +27,7 @@ Vagrant.configure("2") do |config|
   # Network configuration to forward ports.
   config.vm.network :forwarded_port, guest: 80, host: 4567
   config.vm.network :forwarded_port, guest: 8080, host: 4568
+  config.vm.synced_folder ".", "/vagrant", :owner => 'ubuntu'
   
   # Enable provisioning with a shell script. Additional provisioners such as
   # Puppet, Chef, Ansible, Salt, and Docker are also available. Please see the