Added set_description to twython API

src/twython/api.py

@@ -140,8 +140,11 @@ class Twython(EndpointsMixin, object):
         params = params or {}
 
         func = getattr(self.client, method)
-        params, files = _transparent_params(params)
-
+        if type(params) is dict:
+            params, files = _transparent_params(params)
+        else:
+            params = params
+            files = list()
         requests_args = {}
         for k, v in self.client_args.items():
             # Maybe this should be set as a class variable and only done once?
@@ -199,8 +202,10 @@ class Twython(EndpointsMixin, object):
             else:
                 content = response.json()
         except ValueError:
-            raise TwythonError('Response was not valid JSON. \
-                               Unable to decode.')
+            # Send the response as is for working with /media/metadata/create.json.
+            content = response.content
+#            raise TwythonError('Response was not valid JSON. \
+#                               Unable to decode.')
 
         return content
 
@@ -253,10 +258,8 @@ class Twython(EndpointsMixin, object):
             url = endpoint
         else:
             url = '%s/%s.json' % (self.api_url % version, endpoint)
-
         content = self._request(url, method=method, params=params,
                                 api_call=url)
-
         return content
 
     def get(self, endpoint, params=None, version='1.1'):

src/twython/endpoints.py

@@ -14,6 +14,7 @@ This map is organized the order functions are documented at:
 https://dev.twitter.com/docs/api/1.1
 """
 
+import json
 import os
 import warnings
 try:
@@ -145,7 +146,10 @@ class EndpointsMixin(object):
         return self.post('https://upload.twitter.com/1.1/media/upload.json', params=params)
 
     def set_description(self, **params):
-        return self.post('media/metadata/create', params=params)
+    """ Adds a description to an image."""
+        # This method only accepts strings, no dictionaries.
+        params = json.dumps(params)
+        return self.post("media/metadata/create", params=params)
 
     def upload_video(self, media, media_type, size=None):
         """Uploads video file to Twitter servers in chunks. The file will be available to be attached