Heat integration tests failing against https endpoints

Provide ca_file option to pass the ca certificate to verify https
connection. Also pass verify parameter to the test cases which
directly call requests library methods.

Change-Id: I4a81047136d6a64b151180e95c254edea8165349
Closes-Bug: #1553898
diff --git a/scenario/test_autoscaling_lb.py b/scenario/test_autoscaling_lb.py
index e3de091..f5b292e 100644
--- a/scenario/test_autoscaling_lb.py
+++ b/scenario/test_autoscaling_lb.py
@@ -39,7 +39,7 @@
         for count in range(retries):
             time.sleep(1)
             try:
-                r = requests.get(url)
+                r = requests.get(url, verify=self.verify_cert)
             except requests.exceptions.ConnectionError:
                 # The LB may not be up yet, let's retry
                 continue