the openshiftpods driver had some duplicated code from
the openshift driver that wasn't working as expected; the
main issues being:
1. the 'max-pods' config field wasn't taken into account
2. the 'max-servers' config field didn't pass the config validator
despite being correct
This refactor fixes both issues and removes redundant code, which
should improve maintainability in the future.
Add validation to ensure aliases are mutually exclusive in these
providers' configurations.
Add testing to validate this behavior.
Change-Id: Iea8c898c4c2ce61d138d280bd2fadd9cbe8e8b61