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
Bug 1032746: add george's SSH key, and remove old node definition; a=nodechange
bug 1075705: install osslsigncode on linux signing machines. r=dustin
Backout "Bug 1075622: set mark's SSH config"

original commit: 930ea532476bb3ebe13a7e898eac2ceb566f478a
Update buildmaster templates.
Bug 945427 - Add custom valgrind repo for 3.10.0; r=dustin
Bug 1075675: Deploy google oauth key. r=catlee
Merge branch 'master' of https://github.com/mozilla/build-puppet into osslsigncode
Add osslsigncode to signing servers.
Update signing test files package.