Add tempest tests for os-host/{host-name} api

Add tempest tests for nova api 'os-host/{host-name}' which is used
to expose detail host information such cpu/memory/disk.

Change-Id: I7e164c9f584ce70d6bd467575dc1798f0a53bcee
diff --git a/tempest/services/compute/json/hosts_client.py b/tempest/services/compute/json/hosts_client.py
index 8093d19..30a3f7b 100644
--- a/tempest/services/compute/json/hosts_client.py
+++ b/tempest/services/compute/json/hosts_client.py
@@ -37,3 +37,10 @@
         resp, body = self.get(url)
         body = json.loads(body)
         return resp, body['hosts']
+
+    def show_host_detail(self, hostname):
+        """Show detail information for the host."""
+
+        resp, body = self.get("os-hosts/%s" % str(hostname))
+        body = json.loads(body)
+        return resp, body['host']