remove conditional python dep for Ubuntu 11.04

11.04 has been EOL since 2012-10-28
https://lists.ubuntu.com/archives/ubuntu-announce/2012-October/000165.html
update repository recipe to choose correct arch

- yum repo now requires a switch based on architecture, map each value to
the correct path and select a default of 64-bit.
- apt repo now contains a `stable` distribution, which can be switched
  via attribute