In 6637d216 (lib/zodb: Add zstor_2zurl - way to convert a ZODB storage
into URL to access it) we added zstor_2zurl function to convert a ZODB
storage client object into an URL to access the storage. At that time
the function knew how to understand FileStorage only. Let's add support
for other storages that WCFS will need to support now.

NEO URI scheme matches the one currently used on ZODB/go side. It
semantically needs nexedi/neoppod!18
to be also applied to NEO/py side, but we do not care for now that that
patch is not merged (yet, or forever) because extracted ZURL is used
only with WCFS which uses NEO/go.

NEO support also depends on custom patch to remember SSL credentials on
NEO Client:

neo@a2f192cb

Some preliminary history:

5cb39463    fixup! X wcfs/zeo started to work locally
1cf3b228    X zstor_2zurl += NEO
7f8fa32a    X lib/zodb: zstor_2zurl += NEO/SSL support
e26524df    X wcfs, lib/zodb: DemoStorage support