Changes

* [[ReleaseEngineering/PuppetAgain/Modules/shipit_notifier]] - install and configure shipit_notifier in a python virtualenv

* [[ReleaseEngineering/PuppetAgain/Modules/signingserver]] - configure a signing server instance

* [[ReleaseEngineering/PuppetAgain/Modules/slaveapi]] - configure a slaveapi server instance

* [[ReleaseEngineering/PuppetAgain/Modules/slaverebooter]] - install and configure slaverebooter