Send Content-Type only if there is data, relative post location

.gitignore

@@ -1 +1,3 @@
 docs/_build/*
+*.pyc
+*~

slumber/__init__.py

@@ -98,7 +98,12 @@ def _request(self, method, data=None, params=None):
         if self._store["append_slash"] and not url.endswith("/"):
             url = url + "/"
 
-        resp = self._store["session"].request(method, url, data=data, params=params, headers={"content-type": s.get_content_type(), "accept": s.get_content_type()})
+        headers = {"accept": s.get_content_type()}
+
+        if data is not None:
+            headers["content-type"] = s.get_content_type()
+
+        resp = self._store["session"].request(method, url, data=data, params=params, headers=headers)
 
         if 400 <= resp.status_code <= 499:
             raise exceptions.HttpClientError("Client Error %s: %s" % (resp.status_code, url), response=resp, content=resp.content)
@@ -124,12 +129,17 @@ def post(self, data, **kwargs):
 
         resp = self._request("POST", data=s.dumps(data), params=kwargs)
         if 200 <= resp.status_code <= 299:
-            if resp.status_code == 201:
+            location = resp.headers.get("location")
+            if resp.status_code == 201 and location is not None:
                 # @@@ Hacky, see description in __call__
-                resource_obj = self(url_override=resp.headers["location"])
+                if location.startswith("/"):
+                    resource_obj = self(id=location)
+                else:
+                    resource_obj = self(url_override=location)
                 return resource_obj.get(params=kwargs)
             else:
-                return resp.content
+                if resp.content:
+                    return self.get_serializer().loads(resp.content)
         else:
             # @@@ Need to be Some sort of Error Here or Something
             return