Fix Debian compatibility

APT uses "amd64" instead of "x86_64" as the architecture label. Debian doesn't come with a `nobody` group, but uses `nogroup` instead. However, since the owner is `root`, I used the `root` group as well.

Gluster's repo is a little weird in that "wheezy" is hard-coded in the URL.
This is fine for now, but an even better patch would be to split all this into the os-independent params.pp, with yamldata. Additionally, the fact that this repo is a type and not a class was an early mistake I made.