Make Serializers Dumber

Let's have the serializer just worry about serializing the dict
that we hand it, and move the unicode stuff up to a serialize module.

This should hopefully let us move toward using a version string in
cassettes.

vcr/serializers/jsonserializer.py

@@ -1,5 +1,3 @@
-from vcr.request import Request
-from . import compat
 try:
     import simplejson as json
 except ImportError:
@@ -7,26 +5,16 @@ except ImportError:
 
 
 def deserialize(cassette_string):
-    data = json.loads(cassette_string)
-    requests = [Request._from_dict(r['request']) for r in data]
-    responses = [compat.convert_to_bytes(r['response']) for r in data]
-    return requests, responses
+    return json.loads(cassette_string)
 
 
 def serialize(cassette_dict):
-    data = ([{
-        'request': request._to_dict(),
-        'response': compat.convert_to_unicode(response),
-    } for request, response in zip(
-        cassette_dict['requests'],
-        cassette_dict['responses']
-    )])
     try:
-        return json.dumps(data, indent=4)
+        return json.dumps(cassette_dict, indent=4)
     except UnicodeDecodeError:
         raise UnicodeDecodeError(
             "Error serializing cassette to JSON. ",
             "Does this HTTP interaction contain binary data? ",
-            "If so, use a different serializer (like the yaml serializer) for",
+            "If so, use a different serializer (like the yaml serializer) for ",
             "this request"
         )