Make wait & stop methods work on all threads

Previously, ThreadGroup.wait and ThreadGroup.stop would iterate over
the self.threads list and call the wait or stop method on each one.
This list could potentially be edited concurrently by the _thread_done
callbacks and remove some items in the list.  As a result, the wait
method would not actually wait for all threads in the thread group.

Change-Id: Iad5d3e47c8235eadd52a8193657aebb92158568b
Closes-Bug: #1196525
Python3 support for xmlrpclib

Python3 actually does include xmlrpc(lib). It's just called
xmlrpc.client. The class and function signatures are the
same as the old Python2.x xmlrpclib module.

Adds a note that six.moves should be used once six 1.4.2 is
released. See http://bit.ly/1bqrVzu.

References:

Python 2 xmprpllib doc: http://docs.python.org/2/library/xmlrpclib.html
Python 3 xmlrpc.client doc: http://docs.python.org/3/library/xmlrpc.client.html

Change-Id: I478b56f22d02350a21093a887d9f6fcb84958724
Add IgnoreAttemptedHostsFilter to oslo

IgnoreAttemptedHostsFilter is RetryFilter that is using in nova and
cinder, so we can put it to oslo and then back port it to both nova
and cinder.

Change-Id: Ia355810b106fee14a55f48081301a310979befac
Implements part of bp oslo-more-filters
Merge "Make wait & stop methods work on all threads"
Merge "Add IgnoreAttemptedHostsFilter to oslo"
Merge "Python3 support for xmlrpclib"
Fix violations of H302:import only modules

Comment '# noqa' was missed in some files, led to pep8 warning.
And some modules imported non-module. This patch fixes them.
This is output of violation:
http://logs.openstack.org/77/60977/1/check/gate-oslo-incubator-pep8/4a00515/

Change-Id: Id79bca9820853ecd9f0660a855d7bb2fe42ec806
Fix mis-spellings

Fix mis-spellings as found by the misspellings egg.

Change-Id: Ie66978098ba6d8000fb0ef282b316f42920d8638
Closes-Bug: #1257295
Merge "Fix mis-spellings"
Updated from global requirements

Change-Id: Ia2231de238b0f903680463e63a5e970c36ce81d1
Merge "Updated from global requirements"