fixed issue 1708:gae memcache_contrib does not set the time_expire, thanks Nicholas

VERSION

@@ -1 +1 @@
-Version 2.7.2-stable+timestamp.2013.10.09.11.30.04
+Version 2.7.2-stable+timestamp.2013.10.09.11.56.54

gluon/contrib/gae_memcache.py

@@ -37,7 +37,7 @@ class MemcacheClient(object):
                 self.client.delete(key)
         else:
             value = f()
-            self.client.set(key, (time.time(), value))
+            self.client.set(key, (time.time(), value), time=time_expire)
         return value
 
     def increment(self, key, value=1):