doc: Switch from oslosphinx to openstackdocstheme

Per the manuals migration effort, switch to openstackdocstheme [1]

[1] https://specs.openstack.org/openstack/docs-specs/specs/pike/os-manuals-migration.html

Change-Id: I0463f7d39bd72f1d27cfe3f6d5395608b9ed6b29
diff --git a/tox.ini b/tox.ini
index cc7c544..46b15f4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -37,9 +37,9 @@
 deps =
    Pygments
    docutils
-   sphinx>=1.5.1,<1.6.1
+   sphinx>=1.6.2
    pbr>=2.0.0,!=2.1.0
-   oslosphinx
+   openstackdocstheme>=1.11.0
    nwdiag
    blockdiag
    sphinxcontrib-blockdiag
@@ -53,8 +53,8 @@
 [testenv:venv]
 deps =
    pbr>=2.0.0,!=2.1.0
-   sphinx>=1.5.1,<1.6.1
-   oslosphinx
+   sphinx>=1.6.2
+   openstackdocstheme>=1.11.0
    blockdiag
    sphinxcontrib-blockdiag
    sphinxcontrib-nwdiag