Add keystone entry to datasources.conf

Commit ce7cfcbcf51ec93ca1b9dd30d2c330794d6e39ad introduced a bug due to which
keystone wasn't getting populated in datasources.conf; this fixes it

Change-Id: I2c8b243b635db5884318655b6f2ca8c6ff397761
Merge "Add keystone entry to datasources.conf"