Allows selection of floating IP pool in Javelin

javelin2 doesn't allow selection of a floating-ip pool which are a
necessity to use Javelin on multi-host environments.

This patch allows to add this from the resource definition yaml file.

Change-Id: Ifdb84dc1e8a220dec18fc043e4175d3855b0677f
diff --git a/tempest/cmd/javelin.py b/tempest/cmd/javelin.py
index e970249..e0d8e2b 100755
--- a/tempest/cmd/javelin.py
+++ b/tempest/cmd/javelin.py
@@ -86,6 +86,7 @@
       owner: javelin
       flavor: m1.small
       image: javelin_cirros
+      floating_ip_pool: public
     - name: hoplite
       owner: javelin
       flavor: m1.medium
@@ -858,7 +859,9 @@
         for secgroup in server['secgroups']:
             client.servers.add_security_group(server_id, secgroup)
         if CONF.compute.use_floatingip_for_ssh:
-            floating_ip = client.floating_ips.create_floating_ip()
+            floating_ip_pool = server.get('floating_ip_pool')
+            floating_ip = client.floating_ips.create_floating_ip(
+                pool_name=floating_ip_pool)
             client.floating_ips.associate_floating_ip_to_server(
                 floating_ip['ip'], server_id)