Add support for posting files through requests. closes #121. Possibly #134.

vcr/request.py

@@ -1,3 +1,4 @@
+import StringIO
 from six.moves.urllib.parse import urlparse, parse_qsl
 
 
@@ -26,11 +27,16 @@ class Request(object):
     def __init__(self, method, uri, body, headers):
         self.method = method
         self.uri = uri
-        self.body = body
+        self._was_file = hasattr(body, 'read')
+        self._body = body.read() if self._was_file else body
         self.headers = {}
         for key in headers:
             self.add_header(key, headers[key])
 
+    @property
+    def body(self):
+        return StringIO.StringIO(self._body) if self._was_file else self._body
+
     def add_header(self, key, value):
         # see class docstring for an explanation
         if isinstance(value, (tuple, list)):