For reference, here's what happens when I try to build chef-client and I don't have the asset files:

```
Something went wrong...the Omnibus just ran off the road!

Error raised was:

	      Your omnibus repo is missing the following files required to build Mac
      packages:
      * /Users/ddeleo/oc/omnibus-chef/files/mac_pkg/Resources/background.png
      * /Users/ddeleo/oc/omnibus-chef/files/mac_pkg/Resources/license.html
      * /Users/ddeleo/oc/omnibus-chef/files/mac_pkg/Resources/welcome.html
```