Change how path munging works for sphinx docs

The 'import tools' line is fragile as it depends on how things are
executed as to whether or not '.' is in the python path.

Do the sphinx path munging before importing it.

Also, remove reference to modules/autoindex which does not exist and
thus causes sadness from warning-is-error.

Moves documentation requirements into doc/requirements.txt

Depends-On: Ib121961c5a953a434e7b333cd70f7838a2671f69
Change-Id: I23691aa1d0ea038ec1215e6199015529ddd92de4

test-requirements.txt

@@ -7,7 +7,6 @@ coverage!=4.4,>=4.0 # Apache-2.0
 flake8-import-order==0.12 # LGPLv3
 mock>=2.0.0 # BSD
 python-subunit>=1.0.0 # Apache-2.0/BSD
-os-api-ref>=1.4.0 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 pylint==1.4.5 # GPLv2
 testrepository>=0.0.18 # Apache-2.0/BSD
@@ -18,20 +17,5 @@ doc8>=0.6.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 bandit>=1.1.0 # Apache-2.0
 tempest>=17.1.0 # Apache-2.0
-
-# Docs
-sphinxcontrib-actdiag>=0.8.5 # BSD
-sphinxcontrib-blockdiag>=1.5.4 # BSD
-sphinxcontrib-nwdiag>=0.9.5 # BSD
-sphinxcontrib-seqdiag>=0.8.4 # BSD
-docutils>=0.11 # OSI-Approved Open Source, Public Domain
+# Required for pep8 - doc8 tests
 sphinx>=1.6.2 # BSD
-graphviz!=0.5.0,>=0.4 # MIT License
-openstackdocstheme>=1.17.0 # Apache-2.0
-sadisplay>=0.4.8 # BSD
-
-# This needs to be installed after above modules
-pydotplus>=2.0.2 # MIT License
-pyparsing>=2.1.0 # MIT
-networkx<2.0,>=1.10 # BSD
-