fixup! Add a haproxy cookbook

make attributes documentation a bit prettier
fixup! Add a crowbar-pacemaker wrapper cookbook and switch to it

Add documentation to the helper functions, which are not at all
self-explanatory.
fixup! Add haproxy_servers_for_service helper

Explain what the @@haproxy_servers_cache is and why it is needed.
Also fully document the parameters to #haproxy_servers_for_service.
Merge pull request #1 from aspiers/vuntz-haproxy-fixups

fixups deobfuscating haproxy Chef helpers