Add an extension to show the mac address of a ip in server(s)

This extension adds the OS-EXT-IPS-MAC:mac_addr param
so that users can associate the mac address to the ip of the server in
one API call.

Implement bp: os-ext-ips-mac-api-extension
DocImpact

Change-Id: I01d0b3aa804b5218853a4bb568c85e31b87d04e4
Signed-off-by: Zhi Yan Liu <zhiyanl@cn.ibm.com>
Merge "Add an extension to show the mac address of a ip in server(s)"