Allow to use a datetime.timedelta parameter for Client.set

Closes #145

memcache.py

@@ -49,6 +49,7 @@
 
 import binascii
 from io import BytesIO
+from datetime import timedelta
 import re
 import socket
 import sys
@@ -709,7 +710,7 @@ def set(self, key, val, time=0, min_compress_len=0, noreply=False):
         expire, either as a delta number of seconds, or an absolute
         unix time-since-the-epoch value. See the memcached protocol
         docs section "Storage Commands" for more info on <exptime>. We
-        default to 0 == cache forever.
+        default to 0 == cache forever. Optionnaly now accepts a timedelta.
 
         @param min_compress_len: The threshold length to kick in
         auto-compression of the value using the compressor
@@ -724,6 +725,8 @@ def set(self, key, val, time=0, min_compress_len=0, noreply=False):
         @param noreply: optional parameter instructs the server to not
         send the reply.
         '''
+        if isinstance(time, timedelta):
+            time = int(time.total_seconds())
         return self._set("set", key, val, time, min_compress_len, noreply)
 
     def cas(self, key, val, time=0, min_compress_len=0, noreply=False):