Supply missing cisco_cfg_agent.ini file

cisco_cfg_agent.ini file was missed in the initial commit and
caused neutron startup issues. This patch supplies the proper
ini file and adds it back to neutron setup.cfg.
Also the introduced config options are put in a specific group
instead of default as was in the initial commit.

Change-Id: I74b3b77fe6e196524809580f522f91f3b62f5ba7
Closes-bug: #1351466
Merge "Supply missing cisco_cfg_agent.ini file"