Don't encode standard headers keys but just the x-*-meta- ones. That
fixes py3 to not have them casted as bytes and not properly passed to
the requests kwargs.
Other trivial py3 fixes along the way.
Change-Id: I91b95f32fb2aec9b20892a5bb95fd1bc65d002f3
Coverage for swiftclient.client is 71% with these tests.
Unit tests have been moved into another subdirectory
to separate them from functional tests.
Change-Id: Ib8c4d78f7169cee893f82906f6388a5b06c45602