Previously, we stored the WSGI strings in memcached and returned them when
responding to get_account/container_info calls. This would lead to cache
corruption in a heterogenous py2/py3 cluster such as you would have during
a rolling upgrade.
Now, only store and return native strings.
Change-Id: I8d6f66dfe846493972e433f70bad76a33d204562
ef8818a639