Update stress tests to properly use tempest.config

When tempest.config was switched over to using oslo the stress tests
weren't updated with those changes. Also subsequent changes to the
tempest options were not updated in the stress test suite. This left
the stress tests unusable because it couldn't get the needed
information from config. This commit updates the stress test suite
to properly use tempest.config. It also adds a new section to the
config file for stress test specific options.

Fixes bug 1133012

Change-Id: I1b0c726f53dc0e3e0777e27af3e860d35029f958
diff --git a/stress/config.py b/stress/config.py
index ca86ce5..25cb910 100755
--- a/stress/config.py
+++ b/stress/config.py
@@ -12,8 +12,6 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 
-import ConfigParser
-
 
 class StressConfig(object):
     """Provides configuration information for whitebox stress tests."""
@@ -21,33 +19,27 @@
     def __init__(self, conf):
         self.conf = conf
 
-    def get(self, item_name, default_value=None):
-        try:
-            return self.conf.get("stress", item_name)
-        except (ConfigParser.NoSectionError, ConfigParser.NoOptionError):
-            return default_value
-
     @property
     def host_private_key_path(self):
         """Path to ssh key for logging into compute nodes."""
-        return self.get("host_private_key_path", None)
+        return self.conf.compute.path_to_private_key
 
     @property
     def host_admin_user(self):
         """Username for logging into compute nodes."""
-        return self.get("host_admin_user", None)
+        return self.conf.compute.ssh_user
 
     @property
     def nova_logdir(self):
         """Directory containing log files on the compute nodes."""
-        return self.get("nova_logdir", None)
+        return self.conf.stress.nova_logdir
 
     @property
     def controller(self):
         """Controller host."""
-        return self.get("controller", None)
+        return self.conf.stress.controller
 
     @property
     def max_instances(self):
         """Maximum number of instances to create during test."""
-        return self.get("max_instances", 16)
+        return self.conf.stress.max_instances