Reusing subdata from the first recipient

Note that this will include `substitution_data`, `metadata`, and `tags` from the first recipient.

* Keep substitution data for cc/bcc
* Re-enable ensure_ascii for json.dumps, fixes #128

sparkpost/transmissions.py

@@ -1,4 +1,5 @@
 import base64
+import copy
 import json
 from email.utils import parseaddr
 
@@ -90,10 +91,13 @@ def _format_copies(self, recipients, copies):
         formatted_copies = []
         if len(recipients) > 0:
             formatted_copies = self._extract_recipients(copies)
+            main_recipient = copy.deepcopy(recipients[0])
+            main_recipient.pop('address')
             for recipient in formatted_copies:
                 recipient['address'].update({
                     'header_to': self._format_header_to(recipients[0])
                 })
+                recipient.update(**main_recipient)
         return formatted_copies
 
     def _format_header_to(self, recipient):
@@ -241,8 +245,7 @@ def send(self, **kwargs):
         """
 
         payload = self._translate_keys(**kwargs)
-        results = self.request('POST', self.uri,
-                               data=json.dumps(payload, ensure_ascii=False))
+        results = self.request('POST', self.uri, data=json.dumps(payload))
         return results
 
     def _fetch_get(self, transmission_id):

test/test_transmissions.py

@@ -89,7 +89,8 @@ def test_cc_with_sub_data():
             'address': {
                 'email': 'ccone@example.com',
                 'header_to': 'primary@example.com'
-            }
+            },
+            'substitution_data': {'fake': 'data'}
         }
     ]