plugin ip, params: plugin IP discovery, first draft:

- a dedicated plugin now manage IP discovery, for now it uses external website, but it should implement XEP-0279 soon
    - a permission is requested to user for calling an external website. Once the permission is granted (it's global), it is not asked anymore.
    - the ip is discovered on demand, and cache is kept for the session.
    - memory.params.getParamA has a new parameter use_default, which allow to get None when a parameter is not set, instead of the default value.
        This allow to detected when we need to do the first permission request. memory.getParamA don't have this parameter.

src/memory/params.py

@@ -348,7 +348,7 @@ class Params(object):
         @param node: XML param node
         @param attr: name of the attribute to get (e.g.: 'value' or 'type')
         @param value: user defined value
-        @return: str
+        @return: value (can be str, bool, int, list, None)
         """
         if attr == 'value':
             value_to_use = value if value is not None else node.getAttribute(attr)  # we use value (user defined) if it exist, else we use node's default value
@@ -444,7 +444,7 @@ class Params(object):
         """ Same as getParamA but for bridge: convert non string value to string """
         return self.__type_to_string(self.getParamA(name, category, attr, profile_key))
 
-    def getParamA(self, name, category, attr="value", profile_key=C.PROF_KEY_NONE):
+    def getParamA(self, name, category, attr="value", use_default=True, profile_key=C.PROF_KEY_NONE):
         """Helper method to get a specific attribute.
 
         /!\ This method would return encrypted password values,
@@ -452,6 +452,8 @@ class Params(object):
         @param name: name of the parameter
         @param category: category of the parameter
         @param attr: name of the attribute (default: "value")
+        @parm use_default(bool): if True and attr=='value', return default value if not set
+            else return None if not set
         @param profile: owner of the param (@ALL@ for everyone)
         @return: attribute
         """
@@ -466,6 +468,8 @@ class Params(object):
 
         if node[0] == C.GENERAL:
             value = self._getParam(category, name, C.GENERAL)
+            if value is None and attr=='value' and not use_default:
+                return value
             return self._getAttr(node[1], attr, value)
 
         assert node[0] == C.INDIVIDUAL
@@ -481,6 +485,8 @@ class Params(object):
 
         if attr == "value":
             value = self._getParam(category, name, profile=profile)
+            if value is None and attr=='value' and not use_default:
+                return value
             return self._getAttr(node[1], attr, value)
 
     def asyncGetStringParamA(self, name, category, attr="value", security_limit=C.NO_SECURITY_LIMIT, profile_key=C.PROF_KEY_NONE):
@@ -495,7 +501,7 @@ class Params(object):
         @param category: category of the parameter
         @param attr: name of the attribute (default: "value")
         @param profile: owner of the param (@ALL@ for everyone)
-        @return: Deferred
+        @return (defer.Deferred): parameter value, with corresponding type (bool, int, list, etc)
         """
         node = self._getParamNode(name, category)
         if not node:
@@ -769,6 +775,7 @@ class Params(object):
         @param profile_key (str): %(doc_profile_key)s
         @return: a deferred None value when everything is done
         """
+        # FIXME: setParam should accept the right type for value, not only str !
         if profile_key != C.PROF_KEY_NONE:
             profile = self.getProfileName(profile_key)
             if not profile: