Activate fixture.test_logging tests under Python3

Switch from nosetests to testtools.run to launch Python3 tests.

Change-Id: I5062e166697bd858bdce32251d703488e0282eba
Remove str() from LOG.* and exceptions

gettextutils is expecting to receive unicode strings
rather than basestrings.  A basestring can cause an
unhandled exception in the logging code.  To help avoid
such issues we should remove str() from LOG.* messages and
exceptions.  We have verified that the %s formatting code
properly handle getting strings to unicode where necessary.

This patch also fixes one case where a message object was
being concatenated with '+' .  This, like using str() will
cause logging to fail and needs to be fixed.

See bug https://bugs.launchpad.net/cinder/+bug/1274245 for
the original discussion of this problem.

Fix for oslo.messaging: https://review.openstack.org/90577

Change-Id: Iad7c2284c6b21322b96dc881a82bbbab4ebb208e
Closes-bug:  1286306
Merge "Activate fixture.test_logging tests under Python3"
Activate tests.unit.test_imageutils under Python3

Change-Id: I1bb1a40b29b70e93bc1b68efe2a92196f29a0438
Blueprint: make-python3-compatible
On Python <= 2.6, use simplejson if available

Until Python 2.7, stdlib json module was not boosted with a C extension,
meaning bad performance. Try to use simplejson module if available.

RHEL 6.5 is one of the platforms that still ship Python 2.6.

The original idea of the patch belongs to Miguel Angel Ajo Pelayo @
mangelajo@redhat.com

Change-Id: Ib3dc0b713ed90396919feba018772243b3b9c90f
Closes-Bug: 1314129
Merge "Remove str() from LOG.* and exceptions"
Merge "On Python <= 2.6, use simplejson if available"
Merge "Activate tests.unit.test_imageutils under Python3"