py3: symlink follow-up

- Have the unit tests use WSGI strings, like a real system.
- Port the func tests.

Change-Id: I3a6f409208de45ebf9f55f7f59e4fe6ac6fbe163

tox.ini

@@ -129,6 +129,7 @@ basepython = python3
 commands =
   pip install -U eventlet@git+https://github.com/eventlet/eventlet.git
   nosetests {posargs: \
+    test/functional/test_symlink.py \
     test/functional/tests.py}
 
 [testenv:func-encryption]