No longer check for new git-review releases

* git-review(latest_is_newer,main,print_exit_message)
(update_latest_version): The git-review tool is now being packaged
actively by most operating systems/distributions popular amongst the
current user base, and has been stable without serious usability
bugs for some time. As a result, the expectation is that most users
are now installing from places other than PyPI and so the somewhat
hackish functions which check for and warn users about the existence
of new releases have outlived their usefulness. Removing them to
pave the way for continued ease of maintainability improvements, and
also to be one less annoying thing packagers and users have to
disable downstream.

Closes-Bug: 1212829
Change-Id: I9d2ddea794f2b53d4137f0916de4afa029120f59
Migrate to pbr.

For ease of future source code maintenance by OpenStack developers,
git-review is now adopting the same Python Build Reasonableness as
used by current OpenStack projects.

Closes-Bug: 1179007
Change-Id: I20427b51e84b90dcc1d870a547cdcc5240b4ff0e
Implement integration tests.

Provide intergation testing for the git-review utility. Requires
Gerrit war file (like 2.6.1-gerrit.war) in the .gerrit directory in
the git-review project (like git-review/.gerrit/2.6.1-gerrit.war).

Tests start local Gerrit and create test user and project there to
be used.

Closes-Bug: 1048724
Change-Id: I3242479dcbcf230085178004540992680f3f8e30
Add more deterministic port selection for Gerrit.

Let tests select port based on PID instead of random guessing.

We use last 3 decimal digits of PID so that usually we'll just get a
number of adjacent ports.

Change-Id: I5b402ce52fdb61d749f752563a837406508fb6aa