Standardize some parameters in ec2_key

cloud/ec2_key

@@ -112,9 +112,9 @@ def main():
             name=dict(required=True),
             key_material=dict(required=False),
             ec2_url=dict(aliases=['EC2_URL']),
-            ec2_secret_key=dict(aliases=['EC2_SECRET_KEY', 'aws_secret_key'], no_log=True),
+            ec2_secret_key=dict(aliases=['aws_secret_key', 'secret_key'], no_log=True),
-            ec2_access_key=dict(aliases=['EC2_ACCESS_KEY', 'aws_access_key']),
+            ec2_access_key=dict(aliases=['aws_access_key', 'access_key']),
-            region=dict(choices=['eu-west-1', 'sa-east-1', 'us-east-1', 'ap-northeast-1', 'us-west-2', 'us-west-1', 'ap-southeast-1', 'ap-southeast-2']),
+            region=dict(aliases=['aws_region', 'ec2_region'], choices=AWS_REGIONS),
             state = dict(default='present', choices=['present', 'absent']),
         ),
         supports_check_mode=True,