Fix server bug

In cases were the Content-Length value was greater than the actual
length of the HTTP body being send, the server entered in an infinite
loop.

This was quickly fixed by adding an extra condition to the loop were
the data was read in.

pyss3/server.py

@@ -115,8 +115,9 @@ def __send_as_json__(sock, data):
     def __recvall_body__(sock, data, length):
         """Receive all HTTP message body."""
         body = get_http_body(data)
-        while len(body) < length:
-            body += sock.recv(RECV_BUFFER).decode()
+        while len(body) < length and data:
+            data = sock.recv(RECV_BUFFER).decode()
+            body += data
         return url_decode(body)
 
     @staticmethod