wrong timestamp format

It sends timestamp without seconds, 2011-10-25T13:03Z for example, though they are required. http://xmpp.org/extensions/xep-0082.html#sect-id284095

(In [929e74ad6585]) fix timetsamp in set_location plugin. Fixes #17 (closed)

In changeset a9f32344:

fix timetsamp in set_location plugin. Fixes #17 (closed)