fixups deobfuscating haproxy Chef helpers

[As promised](https://github.com/vuntz/barclamp-pacemaker/commit/e2f3d64060ab07628a640fa0bcd8a8718bca226e#commitcomment-5636151), here are some fixups providing the documentation comments which I would have loved to have when I was initially reviewing crowbar/barclamp-pacemaker#12.  Probably I'm just not as smart as you guys, but when I was reviewing it, I ended up staring at it for hours before it started to make sense.  Adding a few comments which document things like method parameters and data structures can make a review (and any subsequent reading of the code by newcomers) *way* easier.  

I hope this PR helps you make sense of my previous moans - hopefully you can see that these comments I've added are much more useful than comments like "this is a cache for blah, used internally" ;-)

P.S. obviously a rebase is required after merging this PR into your PR branch, in order for the fixups! to get squashed in.