Pin Tempest to 17.2.0 for Pike

17.2.0 eliminates random failures in Kitchen and CI

Change-Id: I503c7583dd1147b63a289e206de354d4bd4b56d7

recipes/setup.rb

@@ -101,7 +101,7 @@ end
 
 git tempest_path do
   repository 'https://github.com/openstack/tempest'
-  reference 'master'
+  reference '17.2.0'
   depth 1
   action :sync
   notifies :run, 'python_execute[install tempest]', :immediately

spec/setup_spec.rb

@@ -95,7 +95,7 @@ describe 'openstack-integration-test::setup' do
         '/opt/tempest'
       ).with(
         repository: 'https://github.com/openstack/tempest',
-        reference: 'master',
+        reference: '17.2.0',
         depth: 1
       )
     end