Add Manifest in order to include AUTHORS and ChangeLog

Unlike in master, where a different method for creating the
sdist tarball is used, we still need a MANIFEST.in here for
including AUTHORS and ChangeLog in the tarball.

Change-Id: I266b04048c383b4f127d336411937b102bfafab3
Fixes: Bug #979958
Use nose skip exception conditionally

testtools and nose disagree on the exception raised for skipping
tests with python < 2.7 (see inline comments for exact details).

This monkey-patches testtools to recognise the nose skip exception.
However, due to nose being deprecated we hide this behind an
environment variable to make it an opt-in fix.

While we're there, modify tempest.test.api.utils @skip_unless_attr
decorator to raise from tempest's BaseTestCase rather than
testtools.TestCase directly.

Conflicts:
	tempest/test.py

Change-Id: I13a8f374e879799870bc9193a1ddbdc8d6abb73c
(cherry picked from commit 98c35f3b430e2b364c1650c08154ce969626af38)
Unskip cli-keystone catalog and help tests

Unskip tests which were skipped before pinning python-keyring to
not-faulty version as per bug 1193164.

This reverts commit 27e8547c31f15708b3ff143a62eb96742b287d26.

Change-Id: I1c4c4a509f4629eb8aeb1963e1c9623338d65453
Merge "Add Manifest in order to include AUTHORS and ChangeLog" into stable/grizzly
Merge "Unskip cli-keystone catalog and help tests" into stable/grizzly
Merge "Use nose skip exception conditionally" into stable/grizzly