(PUP-3642) Remove environment name from URL path

This commit makes some changes to the indirector network layer
such that the environment name is no longer a part of the main
URL path structure.  This will allow us to have a more finite URL space
and run Puppet in the same webserver with other apps, without
worrying about URL collisions.  Instead, the environment becomes a query
parameter.
I *think* this is correct as-is?  In the code you linked, we'd end up with:

`["/node/foo?environment=production", "otherarg1=blah&otherarg2=blah"]`

as the return value from `request_to_uri_and_body`.  Then, this line:

`uri_with_query_string = "#{uri}&#{body}"`

would yield:

`"/node/foo?environment=production&otherarg1=blah&otherarg2=blah"`

Then we'd check to see if the length of that was short enough to do a GET, and if not, we'd do a POST with the original values for `uri` and `body`.

Right?