Rather than change the username now, I'm trying to break this stuff up
into different profiles for Jenkins master and agents, that can coexist
on a single machine rather than be copy-pasted.

Start using the puppet 'future' aka puppet 4 parser now.
This allows us to use explicit data types in parameters and gets us
ready for a migration to puppet 4.

They got caught up in the slave->agent rename but can't be redone yet.

This uses hiera to keep things a little cleaner. It uses an actually
common common.yaml for things like the master and repo IPs and other
shared values, then uses a custom fact, buildfarm_role, to apply
hierarchy specific to that role.

I have not yet changed the puppet invocation as I also need to create
the role modules to complement the profile ones.

With this change and the analogous one in the buildfarm_deployment
repository the different high level roles are refactored from separate
hiera configs and site manifests to a unified hiera hierarchy and role
modules.

The common.yaml hiera data is now actually common and at the base of the
hierarchy. Now there is an extra level: buildfarm_role which is provided
as a custom fact via the `FACTER_buildfarm_role` environment variable.
This is one of agent, master, repo; analogous to the master, repo, slave
directories containing hiera data and a site manifest.

…ture.