Use a URL to .repo file in puppet-opendaylight params

We currently use a human-readable RPM repo name as a puppet-odl param to set which repo to install from. The later logic uses this name and the assumption we're installing from the CentOS CBS repos to do the right thing. While this interface is nice from some perspectives, I think we need the flexibility of just passing a URL to any .repo file. For example, it's not possible to use the new ODL Nexus-hosted repos with this scheme.

This will be a backwards incompatible change and will require a major version bump.