cloudstack: add returns_to_int return handling into utils

It is not uncommon that the API returns string for int values e.g. ports in listFirewallRules or listPortForwardings, 

lib/ansible/module_utils/cloudstack.py

@@ -75,6 +75,8 @@ class AnsibleCloudStack(object):
 
         # Init returns dict for use in subclasses
         self.returns = {}
+        # these values will be casted to int
+        self.returns_to_int = {}
 
         self.module = module
         self._connect()
@@ -408,6 +410,11 @@ class AnsibleCloudStack(object):
                 if search_key in resource:
                     self.result[return_key] = resource[search_key]
 
+            # Bad bad API does not always return int when it should.
+            for search_key, return_key in self.returns_to_int.iteritems():
+                if search_key in resource:
+                    self.result[return_key] = int(resource[search_key])
+
             # Special handling for tags
             if 'tags' in resource:
                 self.result['tags'] = []