Add vcs string to version option output

This commit adds a vcs string to 'tempest --version' output like
'12.0.1.dev122' because it's confusing without vcs when a development
phase, especially.

Change-Id: I4de869c84cefc3e42e8a1416c6deeb29fe72e186
diff --git a/tempest/cmd/main.py b/tempest/cmd/main.py
index acd97a8..641d11c 100644
--- a/tempest/cmd/main.py
+++ b/tempest/cmd/main.py
@@ -26,7 +26,7 @@
     def __init__(self):
         super(Main, self).__init__(
             description='Tempest cli application',
-            version=version.VersionInfo('tempest').version_string(),
+            version=version.VersionInfo('tempest').version_string_with_vcs(),
             command_manager=commandmanager.CommandManager('tempest.cm'),
             deferred_help=True,
             )