add lower-constraints job

Create a tox environment for running the unit tests against the lower
bounds of the dependencies.

Create a lower-constraints.txt to be used to enforce the lower bounds
in those tests.

Add openstack-tox-lower-constraints job to the zuul configuration.

Update PrettyTable dependency so the tests pass.

See http://lists.openstack.org/pipermail/openstack-dev/2018-March/128352.html
for more details.

Change-Id: I59c771ca583fb0ebc9f39314ee68264410f8a173
Depends-On: https://review.openstack.org/555034
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/.zuul.yaml b/.zuul.yaml
index ab4d643..57ad381 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -15,6 +15,8 @@
     check:
       jobs:
         - heatclient-functional
+        - openstack-tox-lower-constraints
     gate:
       jobs:
         - heatclient-functional
+        - openstack-tox-lower-constraints