Closes-Bug: #1597190 - Default gateway was mandatory for new params, …

…made optional

For any interface, either default_gateway can be given or single gateway for the server as in old params

Change-Id: I6e8e4e4dcb0434cd8fc50b44cb4a0f8999546cef

src/server_mgr_main.py

@@ -3277,8 +3277,12 @@ def get_control_ip(self, server):
     def get_control_gateway(self, server):
         control_intf = eval(self.get_control_interface(server))
         for key, value in control_intf.iteritems():
-            return str(IPNetwork(value['gateway']).ip)
-        return ''
+            if 'gateway' in value:
+                return str(IPNetwork(value['gateway']).ip)
+        if 'gateway' in server:
+            return str(IPNetwork(server['gateway']).ip)
+        else:
+            return ''
     # end def get_control_gateway
 
     #Function to get control section for all servers