Add python-qpid 0.18 to EL5 external_deps.json
The external_deps.json file currently can only express a single version, platforms relationship because the dependency name is the key to the dictionary. This file is used by builder.py to determine which dependencies should be included in the mash for different distros.
The python-qpid-0.18-1 dependency already exists in koji. That should be used only on EL5. For the EL6 platform, it should continue to receive 0.26-3.
- Extend external_deps.json to express python-qpid 0.18-1 for EL5 and 0.26-3 for EL6.
- Extend pulp_packaging/ci/build-all.py to work with the new external_deps.py
- Tell bcourt that the builders can be updated to not use MRG anymore, but instead get their python-qpid 0.18 from the Pulp repo for EL5.