Provide a synced folder for the virtualbox provisioner

[KushalP]

By default, spinning up a VM using the VirtualBox provisioner doesn't
set a synced folder which means local development (beyond toying with
docker commands) can't really happen.

This fixes that and means local development can occur.

[kyleconroy]

The /vagrant folder should already be linked to the current folder.

[KushalP]

In my case it wasn't. I'm using vagrant 1.3.1.

[KushalP]

Going to destroy and up my VM and see if it's consistent.

[KushalP]

Yup. You're right. I must have done something wrong on my side.

[KushalP]

No, this change is actually required. There was just some NFS lag in my testing.

[crosbymichael]

ping @mzdaniel

[KushalP]

For completeness, I just checked this against Vagrant 1.3.3 (I was on 1.3.1 previously) and upgraded to VirtualBox 4.2.18 and the same behaviour occurs across two different machines.

[creack]

@KushalP can you rebase?

[KushalP]

@creack rebased 👍

[mzdaniel]

@KushalP: I wasn't able to verify your claim.

daniel@delphy:/go/src/github.com/dotcloud/docker$ vagrant --version
Vagrant 1.3.1
daniel@delphy:/go/src/github.com/dotcloud/docker$ virtualbox --help
Oracle VM VirtualBox Manager 4.2.16
.
.
daniel@delphy:/go/src/github.com/dotcloud/docker$ cat > test
This is a test
daniel@delphy:/go/src/github.com/dotcloud/docker$ vagrant ssh
Welcome to Ubuntu 12.04 LTS (GNU/Linux 3.8.0-31-generic x86_64)

Documentation: https://help.ubuntu.com/
Welcome to your Vagrant-built virtual machine.
Last login: Mon Oct 14 23:16:40 2013 from 10.0.2.2
vagrant@precise64:$ cat /vagrant/test
This is a test
vagrant@precise64:$ cat >/vagrant/test
Test 2
vagrant@precise64:~$ exit
logout
Connection to 127.0.0.1 closed.
daniel@delphy:/go/src/github.com/dotcloud/docker$ cat test
Test 2

[KushalP]

@mzdaniel Okay. I'll close this for now as it seems specific to my machine.