Allow cobbler nodes to be created as yaml

This commit adds a nodes variable to the
cobbler_server profile that can be used to
consume a hash of cobbler nodes defined in
hiera under the key: cobbler_nodes.

This change is made for two reasons:

1. the cobbler profile should be responsible for
configuring its own nodes
2. it ensures that cobbler nodes are only configured
when cobbler is configured.
Add apache profile

This commit adds an apache profile which serves
as a central location to configure apache so that
it can be configured, and still used as a dependency
for multiple services.

This change is required b/c of 41b0a42b07f6681e01363d7d5738e5f46d747f64
from naginator which includes apache::mod::php which requires
that apache is configured to use prefork to manage processes.