Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/21471

Log:
commit 80bd1de65a3b8e7502ece9cedca3c027d176de39
Author: Vishvananda Ishaya <vishvananda at gmail.com>
Date:   Thu Feb 7 14:46:08 2013 -0800

    Simplify and optimize az server output extension.
    
    Displaying two different az results to users is confusing, so just
    return the az that the instance is actually in. Also, cache the
    result from looking up the az by host for an hour to avoid making
    lots of expensive db requests.
    
    DocImpact
    
    Change-Id: Ib39bf94c608874695aab00e61035e64f9594a985