Add role to build the stackviz report

Add a role to build the stackviz report and include it in the
tempest post play.

Change-Id: I085460fc7a4fe6baee2d85c8ab3ea3a2128ea54d
diff --git a/roles/process-stackviz/defaults/main.yaml b/roles/process-stackviz/defaults/main.yaml
new file mode 100644
index 0000000..b1eb8d9
--- /dev/null
+++ b/roles/process-stackviz/defaults/main.yaml
@@ -0,0 +1,3 @@
+devstack_base_dir: /opt/stack
+stage_dir: /opt/stack/
+test_results_stage_name: test_results