cloudstack: add choices for api_http_method

lib/ansible/modules/extras/cloud/cloudstack/cs_affinitygroup.py

@@ -71,7 +71,6 @@ EXAMPLES = '''
     name: haproxy
     affinty_type: host anti-affinity
 
-
 # Remove a affinity group
 - local_action:
     module: cs_affinitygroup
@@ -220,7 +219,7 @@ def main():
             api_key = dict(default=None),
             api_secret = dict(default=None, no_log=True),
             api_url = dict(default=None),
-            api_http_method = dict(default='get'),
+            api_http_method = dict(choices=['get', 'post'], default='get'),
             api_timeout = dict(type='int', default=10),
         ),
         required_together = (