Simplify docs build

Remove unnecessary old code from tools/build_docs.sh; it now only builds
docs for the current branch in the current working directory.

Fix the merging if the git log changes into changes.html.

Change-Id: I965dc3383b6317807ca0d47fe42648a19e96b57b
diff --git a/tox.ini b/tox.ini
index c8d3909..a958ae7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -36,5 +36,5 @@
   TOP_DIR={toxinidir}
   INSTALL_SHOCCO=true
 commands = 
-	bash tools/build_docs.sh
 	python setup.py build_sphinx
+	bash tools/build_docs.sh