remove commented out PXE boot VMs

B/C they are no longer being used
Port build node to node data

This commit ports the existing build server role
to be something described completely as data.

This fix is intended to make it easier to combine
this role with other roles to form new roles (
specifically the super all in one with os all in one
+ build + cache)

The patch contains the following parts:
* add support for arrays of post config actions
* remove build server roles
* allow data nodes to express if they want to
use puppet agent or apply (b/c the build node
must use apply)
* allow the apply_manifest to accept a certificate
(in case we need to pass it for site.pp runs)
* remove hardcoded RedHat and Ubuntu builds from
Vagrantfile
* Add new role to 2_role node and scenario
* Add new node to all in one scenario
* add it to role_mapper
* remove node entry from site.pp
* add new build_node class group
Merge pull request #75 from bodepd/data_build_node

Data build node