Pass in service name to nova constructor.

Because, you know, we should have to do this.

Rackspace publishes two things called "compute" into their catalog for
customers who still have the old compute service.

Change-Id: I27d5a78fc743057a270acd4bf7c85fd998f9074d

launch/launch-node.py

@@ -32,6 +32,7 @@ NOVA_PASSWORD = os.environ['OS_PASSWORD']
 NOVA_URL = os.environ['OS_AUTH_URL']
 NOVA_PROJECT_ID = os.environ['OS_TENANT_NAME']
 NOVA_REGION_NAME = os.environ['OS_REGION_NAME']
+NOVA_SERVICE_NAME = os.environ.get('OS_SERVICE_NAME', 'compute')
 NOVACLIENT_INSECURE = os.getenv('NOVACLIENT_INSECURE', None)
 IPV6 = os.environ.get('IPV6', '0') is 1
 
@@ -43,6 +44,7 @@ def get_client():
     kwargs = {}
     kwargs['region_name'] = NOVA_REGION_NAME
     kwargs['service_type'] = 'compute'
+    kwargs['service_name'] = NOVA_SERVICE_NAME
 
     if NOVACLIENT_INSECURE:
         kwargs['insecure'] = True