Make a cStringIO usage in test_log py3 compatible

Change-Id: Ibee1f3eb25961cdb9383e1bb42138ef7391b98c2
Signed-off-by: Julien Danjou <julien@danjou.info>
Update requirements

This is the fabulous result of running the update.py script from
openstack/requirements with this repository as the target. It therefore
updates all dependencies, with nice version numbers that this repository
have to use to work. It also fixes case on some dependencies.
This update also brings a brand shiny new setup.py automatically handled
and generate by this same openstack/requirements repository.

Due to some changes somewhere, testr configuration has to be modified,
and I actually fixed and simplified a bit to make tests ran.

Change-Id: Ibbea49fbc98caa6a175e9174243ab66a753493f8
Merge "Update requirements"
Merge "Make a cStringIO usage in test_log py3 compatible"
Make dependency on netaddr optional

https://review.openstack.org/#/c/38023/ pointed out that
the dependency on netaddr is unnecessary and can be avoided.
Use try_import to avoid a hard dependency on netaddr.

Change-Id: I8b246f20f9001379fcb5ca3a84aabee3847cb945