Update Sphinx and modules versions

- Only build branches, not every point release
- Bump site copyright date
- Remove a few unused sphinx extensions

Change-Id: I96468446f1f85fdff2daf5a9e1e7e8b85b61b378
diff --git a/VERSION b/VERSION
index 766d708..e43686a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.8.5
+2.8.6