Create repository and package signing keys
If we're going to be offering users nightly/weekly package builds, we want to offer them some modicum of proof that they came from us, and are what they claim to be, to the best of a robot's ability to verify them. The current plan is that all release builds/packages will be signed by hand, but for the nightlies/weeklies/whateverlies we need to create signing keys that can sign things automatically.