Avoid mixing up backend servers

If an haproxy::listen and haproxy::backend have the same name, their
order will be `20-<name>-00` and concat ordering will be mixed up. The
haproxy::balancermember resource uses this ordering to add backend
servers to a listen/backend block (with the order `20-<name>-01`) and
this is the least-impactful way to avoid balancer members from being
cross-associated without introducing backwards-incompatible changes.
Update the readme to look something like the readme template
Correctly privetize define
Merge pull request #96 from hunner/update_readme

Update the readme to look something like the readme template
Merge pull request #95 from hunner/private_define

Correctly privetize define
Merge pull request #92 from hunner/mix_backends

Avoid mixing up backend servers
Update specs with lots of test cases

The C\d{4} numbers are for our internal test tracking.
Merge pull request #97 from hunner/update_specs

Update specs with lots of test cases