httplib2 makes use of the ssl module provided by Python; under Python 2,
the ssl module does not support IP addresses as subject alternate names
(SAN's) which although an optional part of the associated RFC, is awkward
to work with in environments where certificate management approaches
rely on use of IP addresses in SAN's.
The requests module is more than happy to deal with this scenario; switch
to requests in preference of httplib2 for metadata proxy calls.
httplib2 is retained as its used elsewhere in the codebase.
(cherry picked from commit 7e0dd2f18d4919964655cfce7a282d1c5c131fc4)