remove chef-server project (moved to omnibus-chef-server)

It makes most sense to only have one logical project type per git 
repository. The main reason for this convention is versioning is driven 
through annotated git tagging. So in the case of chef-client having the 
`chef` and `chef-windows` projects together is OK since:

* Both projects build packages for `chef-client`.
* Both projects are versioned at the same time.
* Both projects are built at the same time.
Update README with new location of chef-server project.
Merge pull request #67 from opscode/remove-server-project

remove chef-server project (moved to omnibus-chef-server)