(PUP-3644) Move urls to v3

This removes the "v1" HTTP API, which mounted
all of the various Puppet endpoints at "/" on the webserver.

In its place we now have the "v3" API, which includes
the versioned "/v3" prefix for all of the indirected URLs.
oh, yeah... this is only used for that 'environments' endpoint, and is ported straight over from v2.0, so I think it should be fine.