Add support for Swift v1 auth

Unfortunately, `python-swiftclient` doesn't work well with python3, so
we have to continue building out our own home-baked Swift client.

If in the future `python-swiftclient` does get patched to work with py3,
we simplify this code and remove the `miniswift` module.
test_miniswift: expand auth tests to cover v1 & v?

This adds cases to test the v1 auth, and also to test what happens when
an unknown auth version is specified.
zpm: catch ZPMExceptions, print error messages

... without stacktraces.