updating machines of a job with multiple azs should not affect multiple azs at once
updating machines of a job with multiple azs should not affect multiple azs at once

The code is more complex than strictly necessary to accommodate
Dmitriy's concern that Hashes aren't necessarily enumerated properly
JRuby, for example, may not adhere to the official Ruby docs.
http://ruby-doc.org/core-1.9.3/Hash.html

Hashes enumerate their values in the order that the corresponding keys
were inserted.

Signed-off-by: Danny Berger <8efccf38e9d8f361e1973ad644e1b1e50ad8ecfe@pivotal.io>

barthy1/bosh,barthy1/bosh,barthy1/bosh,barthy1/bosh