Clean up openstack-common.conf

The issues are detected by new change about update.py
in I68c0108304be8a315bcefe939c22019caab9bc98. This patch
doesn't depend the oslo-incubator patch.
 * remove unused module config
 * add missing module loopingcall and remove module
   cfg in openstack-common.conf
 * sort the modules in openstack-common.conf

Closes-Bug: #1323622
Change-Id: I10cca7386ea8e586f7e35a2f0e5b3c5c14906d7e
Merge "Clean up openstack-common.conf"