Add subunit-describe-calls

Adds new command subunit-describe-calls, documentation,
and unittests.

subunit-describe-calls is a parser for subunit v1 & v2 streams to
determine what REST API calls are made inside of a test and in what
order they are called.

Later commits will add additional functionality relating to request
& response headers & body data along with a stdout output option and
stdin input.

Change-Id: I468d0d3e3b6098da95a81cc86d9bdd1b47ee1f03
diff --git a/setup.cfg b/setup.cfg
index 0bf493c..56344b0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -34,6 +34,7 @@
     tempest = tempest.cmd.main:main
     skip-tracker = tempest.lib.cmd.skip_tracker:main
     check-uuid = tempest.lib.cmd.check_uuid:run
+    subunit-describe-calls = tempest.cmd.subunit_describe_calls:entry_point
 tempest.cm =
     account-generator = tempest.cmd.account_generator:TempestAccountGenerator
     init = tempest.cmd.init:TempestInit