Config logABug feature for Keystone api-ref

Currently, Keystone api-ref is not configured with logABug feature.
When users click "Report bug" button, it leads to
"bugs.launchpad.net/openstack-manuals" which is default.
We should change it to "bugs.launchpad.net/keystone/"

Change-Id: I8d6fc4d2a6ab9d7f444a02cbc2f756fdaa3de264

api-ref/source/conf.py

@@ -97,6 +97,15 @@ version = keystone_version.release_string()
 # The full version, including alpha/beta/rc tags.
 release = keystone_version.release_string()
 
+# Config logABug feature
+giturl = (
+    u'http://git.openstack.org/cgit/openstack/keystone/tree/api-ref/source')
+# source tree
+# html_context allows us to pass arbitrary values into the html template
+html_context = {"bug_tag": "api-ref",
+                "giturl": giturl,
+                "bug_project": "keystone"}
+
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 # language = None