Add XEP-0115 plugin.

Finally

sleekxmpp/plugins/xep_0115/stanza.py

@@ -0,0 +1,19 @@
+"""
+    SleekXMPP: The Sleek XMPP Library
+    Copyright (C) 2011 Nathanael C. Fritz, Lance J.T. Stout
+    This file is part of SleekXMPP.
+
+    See the file LICENSE for copying permission.
+"""
+
+from __future__ import unicode_literals
+
+from sleekxmpp.xmlstream import ElementBase, ET
+
+
+class Capabilities(ElementBase):
+
+    namespace = 'http://jabber.org/protocol/caps'
+    name = 'c'
+    plugin_attrib = 'caps'
+    interfaces = set(('hash', 'node', 'ver', 'ext'))