Fix MismatchError in test_host_name_is_same_as_server_name

Nova has lowercased hostnames since 2011.
Add lower() method to self.name.

Change-Id: I87f3326b8cdab0fe6392b14daa7fb89f6e971392
Closes-bug: #1618875
diff --git a/tempest/api/compute/servers/test_create_server.py b/tempest/api/compute/servers/test_create_server.py
index e8df52d..78f0db4 100755
--- a/tempest/api/compute/servers/test_create_server.py
+++ b/tempest/api/compute/servers/test_create_server.py
@@ -139,7 +139,7 @@
         hostname = linux_client.get_hostname()
         msg = ('Failed while verifying servername equals hostname. Expected '
                'hostname "%s" but got "%s".' % (self.name, hostname))
-        self.assertEqual(self.name, hostname, msg)
+        self.assertEqual(self.name.lower(), hostname, msg)
 
     @test.idempotent_id('ed20d3fb-9d1f-4329-b160-543fbd5d9811')
     def test_create_server_with_scheduler_hint_group(self):