Add profiler support into Tempest

The primary goal is to be able to run all Tempest tests
and verify OpenStack when profiling is enabled. Also this patch
allows to:
 * manually verify that certain services are properly instrumented
   and produce trace events when a scenario is executed;
 * write automatic tests for trace coverage;
 * profile certain tests from performance perspective.

A new parameter is introduced into tempest.conf:
 * profiler.key - the key used to enable OSProfiler (should
     match the one configured in OpenStack services)

To test the patch on DevStack:
 1. Enable osprofiler with Redis collector in local.conf:

   enable_plugin osprofiler https://git.openstack.org/openstack/osprofiler master
   OSPROFILER_COLLECTOR=redis

 2. Run all Tempest tests or select some, e.g.:

   tempest run --regex tempest.api.network.test_networks.NetworksTest.test_list_networks*

Change-Id: I64f30c36adbf7fb26609142f22d3e305ac9e82b5
diff --git a/releasenotes/notes/add-profiler-config-options-db7c4ae6d338ee5c.yaml b/releasenotes/notes/add-profiler-config-options-db7c4ae6d338ee5c.yaml
new file mode 100644
index 0000000..2245044
--- /dev/null
+++ b/releasenotes/notes/add-profiler-config-options-db7c4ae6d338ee5c.yaml
@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Add support of `OSProfiler library`_ for profiling and distributed
+    tracing of OpenStack. A new config option ``key`` in section ``profiler``
+    is added, the option sets the secret key used to enable profiling in
+    OpenStack services. The value needs to correspond to the one specified
+    in [profiler]/hmac_keys option of OpenStack services.
+
+    .. _OSProfiler library: https://docs.openstack.org/osprofiler/