QA: add support for burnin rename

This patch adds support for optionally doing the rename burnin test, and
adds an example to the sample QA file. To disable, either remove or
specify an empty rename target.

Reviewed-by: imsnah

qa/qa-sample.json

@@ -90,7 +90,8 @@
     "burnin-instances": 2,
     "burnin-disk-template": "drbd",
     "burnin-in-parallel": false,
-    "burnin-check-instances": false
+    "burnin-check-instances": false,
+    "burnin-rename": "xen-test-rename"
   },
 
   "# vim: set syntax=javascript :": null

qa/qa_cluster.py

@@ -152,6 +152,7 @@ def TestClusterBurnin():
   disk_template = options.get('burnin-disk-template', 'drbd')
   parallel = options.get('burnin-in-parallel', False)
   check_inst = options.get('burnin-check-instances', False)
+  do_rename = options.get('burnin-rename', '')
 
   # Get as many instances as we need
   instances = []
@@ -179,6 +180,8 @@ def TestClusterBurnin():
         cmd.append('--parallel')
       if check_inst:
         cmd.append('--http-check')
+      if do_rename:
+        cmd.append('--rename=%s' % do_rename)
       cmd += [inst['name'] for inst in instances]
       AssertEqual(StartSSH(master['primary'],
                            utils.ShellQuoteArgs(cmd)).wait(), 0)