Register heat tempest plugin

This allows heat_integrationtests tests to be run with the current
method *or* with the tempest runner. To run with tempest, configure
heat_integrationtests/heat_integrationtests.conf as before, then add
the following to the configured tempest.conf:

  [service_available]
  heat_plugin = True

Then run with tempest, for example

  tempest run --regex heat_integrationtests

The next step will be for tempest runs to take configuration values
from tempest.conf rather than heat_integrationtests.conf

blueprint tempest-plugin-support

Change-Id: I920a6616dbd79092d5bf9a8c4f48da2f94c0a326
diff --git a/common/config.py b/common/config.py
index fd6ccbf..f4df28b 100644
--- a/common/config.py
+++ b/common/config.py
@@ -16,6 +16,14 @@
 
 import heat_integrationtests
 
+service_available_group = cfg.OptGroup(name="service_available",
+                                       title="Available OpenStack Services")
+
+ServiceAvailableGroup = [
+    cfg.BoolOpt("heat_plugin",
+                default=True,
+                help="Whether or not heat is expected to be available"),
+]
 
 heat_group = cfg.OptGroup(name="heat_plugin",
                           title="Heat Service Options")
@@ -174,3 +182,4 @@
 
 def list_opts():
     yield heat_group.name, HeatGroup
+    yield service_available_group.name, ServiceAvailableGroup