Bug 1032746: Puppetize proxxy; r=dustin

Some highlights:

* I'm using new nginx-development repository which is mirrored from Nginx Mainline PPA because we need a recent version of nginx that is capable of logging to syslog.
* proxxy module requires one new secret: proxxy_pvtbuilds_password (see bug 1035891)
* designed and tested on Ubuntu 14.04, though may work on 12.04
Bug 1032746: add node def for proxxy; r=gmiroshnykov