Add an alias and make sure tagging works for names even if no other tags specified.

playbooks/library/ec2_subnet

@@ -176,8 +176,9 @@ class SubnetManager:
         :return: None
         """
         tags = {'Name': self.name}
-        for tag in self.tags:
-            tags[tag['key']] = tag['value']
+        if self.tags:
+            for tag in self.tags:
+                tags[tag['key']] = tag['value']
 
         self.subnet.add_tags(tags)
 
@@ -189,7 +190,7 @@ def main():
             name=dict(required=True, type='str'),
             state=dict(default='present', choices=['present', 'absent']),
             vpc_id=dict(required=True, type='str'),
-            cidr_block=dict(required=True, type='str'),
+            cidr_block=dict(required=True, type='str', aliases=['cidr']),
             az=dict(required=True, type='str'),
             route_table_id=dict(required=True, type='str'),
             network_acl_id=dict(type='str'),