Add HTML email

Make the SES client optionally pass through HTML and text body, as per:
http://docs.aws.amazon.com/ses/latest/APIReference/API_Body.html

Gets the message as HTML from:
https://github.com/alphagov/notifications-utils/pull/12

app/celery/tasks.py

@@ -267,7 +267,8 @@ def send_email(service_id, notification_id, subject, from_address, encrypted_not
                     from_address,
                     notification['to'],
                     subject,
-                    template.replaced
+                    body=template.replaced,
+                    html_body=template.as_HTML_email,
                 )
                 update_notification_reference_by_id(notification_id, reference)
             except AwsSesClientException as e:

app/clients/email/aws_ses.py

@@ -41,6 +41,7 @@ class AwsSesClient(EmailClient):
                    to_addresses,
                    subject,
                    body,
+                   html_body='',
                    reply_to_addresses=None):
         try:
             if isinstance(to_addresses, str):
@@ -50,6 +51,15 @@ class AwsSesClient(EmailClient):
             elif reply_to_addresses is None:
                 reply_to_addresses = []
 
+            body = {
+                'Text': {'Data': body}
+            }
+
+            if html_body:
+                body.update({
+                    'Html': {'Data': html_body}
+                })
+
             start_time = monotonic()
             response = self._client.send_email(
                 Source=source,
@@ -62,9 +72,7 @@ class AwsSesClient(EmailClient):
                     'Subject': {
                         'Data': subject,
                     },
-                    'Body': {
-                        'Text': {
-                            'Data': body}}
+                    'Body': body
                 },
                 ReplyToAddresses=reply_to_addresses)
             elapsed_time = monotonic() - start_time