1、As mentioned in [1], we should avoid using six.iteritems/keys
   achieve iterators. We can use dict.items/keys instead, as it
   will return iterators in PY3 as well. And dict.items/keys will
   more readable.
2、In py2, the performance about list should be negligible,
   see the link [2].

  [1] https://wiki.openstack.org/wiki/Python3
  [2] http://lists.openstack.org/pipermail/openstack-dev/
      2015-June/066391.html

TrivialFix.

Change-Id: I0cbe8af3210233a58d25f0df187c3d085405aa2a

There were some problems in the documentaiton that
prevented tox -e docs from working.  Also changed
attention to WARNING since attention was not as eye-grabbing
as I'd hoped during a previous review.

Change-Id: I2b661afa2cd4a4331bbcc99240d3e127a5d94a11

Upgrade Ubuntu base image to Xenial

Closes-Bug: #1593599
Change-Id: I5832a729a9a4fa73c02442047c92ba088ce20db3

In CI environment, MySQL-python wheel package has a wrong _mysql.so
file, which is not compatible with Ubuntu.

Disable wheel index in the CI for pip.

Closes-Bug: #1615231
Change-Id: I127ebb017e09a5bf245e0fdad9bf052203e68e55

TrivialFix

Change-Id: Ib2474257554e0b294bc39a658108326fcbbdbe58

The location for the Kolla configurations in the workflow for evaluation
needs to be fixed correctly to /usr/share/kolla/etc_examples

This was brought up on IRC -
http://eavesdrop.openstack.org/irclogs/%23openstack-kolla/%23openstack-kolla.2016-08-18.log.html#t2016-08-18T21:02:18

Change-Id: Ie9f651308a7b51cfd3ad1c617637bab1b5cc568e

Currently if the install_packages macro is run with an empty
package list, it will add a yum or apt-get command with no
packages listed.

This bug fix aims to omit this line when no packages have
been given, or, the operator wants to use the "_override" /
"_remove" functionality to disable all packages being
installed in a Dockerfile.

Co-Authored-By: Paul Bourke <paul.bourke@oracle.com>
Change-Id: Ifaaaebfccc3adb0f2f68a35ac08e59378bc87fdb
Closes-bug: 1612446

Add the following prechecks for network_interface:

* Check it exists on the node
* Check its up
* Check it has an IP associated

TrivialFix
Change-Id: I86f1d79d8592a3b108822e7d19541f91a1c0d716
Co-Authored-By: James McCarthy <james.m.mccarthy@oracle.com>

Change-Id: Ic5710257758d3b6c8655443a5498cfa64d756263

Change-Id: I30c4d7929940c751bf88c4bf9a0e200025ebd5c8
Partially-Implements: blueprint enable-congress-container

TrivialFix

Change-Id: I735091c4d044344361e604014f3877b608223204