python3: Fix python3 tox installation

Fix python3 tox installation so that it uses setuptools
by default rather than use distribute.

Also bump the version used by teestrepository so that
it uses a more python3 compliant version.

Change-Id: If2522f12889e66cedc6286d48ba8105c685e6e0e
Signed-off-by: Chuck Short <chuck.short@canonical.com>