plugin XEP-0060: added node watching methods to bridge:

new methods psNodeWatchAdd and psNodeWatchRemove allows to set a watch for the time of the session on one node, to have a signal called when something change on this node.
This signal (psEventRaw) send raw data (raw XML), in opposition to psEvent which is there to send high level data (e.g. parsed blog data).
Those method are primarely there to let frontends manage local cache for pubsub nodes.

src/plugins/plugin_exp_pubsub_hook.py

@@ -179,7 +179,7 @@ class PubsubHook(object):
             - HOOK_TYPE_PYTHON_FILE: a python file
                 file must have a "hook" method which will be called
             - HOOK_TYPE_PYTHON_CODE: direct python code
-            /!\ Python hooks will be executed in SàT context,
+                /!\ Python hooks will be executed in SàT context,
                 with host, client and item as arguments, it means that:
                     - they can do whatever they wants, so don't run untrusted hooks
                     - they MUST NOT BLOCK, they are run in Twisted async environment and blocking would block whole SàT process