Creating symbolic link for plugin.ini

We need create the link for plugin.ini on rhel, centos, fedora
platforms, otherwise the neutron-server can not be started. Here is the
bug from community:
https://bugs.launchpad.net/openstack-manuals/+bug/1240697

Closes-Bug: #1268670
Change-Id: I6f0fdc0a7610ba55e8cd7051805fd5883e41c87e
change default neutron quota driver

Fixes: bug 1280361

The default in Havana is no longer to use the config file backed quota
driver.  Instead, it is to use:

neutron.db.quota_db.DbQuotaDriver

This commit alters the attribute to use this driver by default.

Change-Id: I0bd2661f9a12cf82c113f91c41cba3ff3f1096a8
Merge "change default neutron quota driver"