A quick fix to ensure Neutron works with endpoint definitions that are not version-agnostic.
The service-side API will always have a v2.0 in the path.
However, the endpoint will sometimes contain a v2.0 and sometimes it will not.
The VersionAwareRegionToEndpoint ensures that the endpoint will always look the same
before /v2.0 is added to it.
Cannot leave labs until fixed:
This code will be unnecessary once this is supported.
apply in interface com.google.common.base.Function<Object,URI>