(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.
I think that the only reason we moved this stuff into the 'uri2indirection' method was because in the original branch, we needed to be able to pull in the indirector model object earlier so that we could pull the environment out of it.

I think that since we rolled that back, we don't technically need this part of the refactor anymore; `uri2indirection` can still return `indirection_name` as it does in the current HEAD, and then we can do the auth check here like we already were.

Functionally I don't think it necessarily matters, so I'm OK leaving it like this if it would cause much additional work to put it back the way that it was... but if it's easy, we might as well switch it back so that the diff is smaller.  Slightly less risk that way :)