Allows nginx to reverse proxy both services

[bmbouter]

Without this urls outside of /pulp/content/ and /pulp/api/ would not
route correctly. This causes the last block to try both services if the
first one 404s.

https://pulp.plan.io/issues/4966
closes #4966

[bmbouter]

Here's how I test this by requesting 3 URLs.

First I request http localhost/pulp/api/v3/status/ and I see this in the logs:

Aug 06 19:45:33 pulp3-source-fedora28.localhost.example.com gunicorn[27775]: 127.0.0.1 - admin [06/Aug/2019:19:45:33 +0000] "GET /pulp/api/v3/status/ HTTP/1.0" 200 1330 "-" "HTTPie/0.9.4"

Notice it's on port 27775. Then I request http localhost/pulp/content/asdf/ and I see this in the logs:

Aug 06 19:45:51 pulp3-source-fedora28.localhost.example.com gunicorn[28294]: 127.0.0.1 [06/Aug/2019:19:45:51 +0000] "GET /pulp/content/asdf/ HTTP/1.0" 404 172 "-" "HTTPie/0.9.4"

Notice it's on port 28294. Then I request from one that isn't in /pulp/content/ or /pulp/api so I request http localhost/neither and I see this in the logs:

Aug 06 19:46:25 pulp3-source-fedora28.localhost.example.com gunicorn[27775]: pulp: django.request:WARNING: Not Found: /neither
Aug 06 19:46:25 pulp3-source-fedora28.localhost.example.com gunicorn[28294]: 127.0.0.1 [06/Aug/2019:19:46:25 +0000] "GET /neither HTTP/1.0" 404 172 "-" "HTTPie/0.9.4"
Aug 06 19:46:25 pulp3-source-fedora28.localhost.example.com gunicorn[27775]: 127.0.0.1 - admin [06/Aug/2019:19:46:25 +0000] "GET /neither HTTP/1.0" 404 77 "-" "HTTPie/0.9.4"

See how that url is requested from both backends by their port numbers!

[dkliban]

Thank you!