Restructure project layout to closer match Stackato hosting enviroment

Restructures the project layout as follows:

```
HOST                                      VM                            Comment
app/public              ->               /app/app/public           Webroot
app/db                   ->               /app/app/db                DB dumps, installed by bin/start.sh
app/Rakefile           ->               /app/app/Rakefile        build script
app/stackato.yml    ->               /app/app/stackato.yml Deploy options
                                               /app/buildpack            Cloned mrdavidlaing/stackato-buildpack-wordpress 
dev_server             ->               /vagrant                      All the stuff to launch & configure the  dev VM
```

Note that:

1.  Everything on the VM happens in `/app`; just like Stackato
1.  The concept of `VM:src/` and `VM:dist/` is gone.  Edit the files in `HOST::app/`, and they get automatically synced into `VM:/app/app`  **
1.  `VM:/app/buildpack/compile` adds extra files (wordpress, config, runtimes) to `VM:/app/app`, but these are NOT synced back to `HOST:app`.  This keeps `HOST:app` nice and clean, so you are only editing _your_ files.

** Hiphop-php doesn't detect file changes in a Vagrant shared folder.  To get around this we setup a Vagrant shared_folder to map `HOST:app` -> `VM:/tmp/app_on_host`.  `VM:/vagrant/sync_app_on_host_2_app.sh` runs in the background, polling for file changes in `VM:/tmp/app_on_host` which it then copies to `VM:/app/app`. Note that this is one way only. See `dev_server/sync_app_on_host_2_app.log` for details of what syncing is going on.