clean PLC log only if there is something to clean

Otherwise exception happens in Beremiz service.

Traceback (most recent call last):
File "/home/developer/WorkData/PLC/beremiz/beremiz/connectors/PYRO/_init_.py", line 113, in catcher_func
return func(*args, **kwargs)
File "/home/developer/WorkData/PLC/beremiz/beremiz/connectors/PYRO/_init_.py", line 194, in my_local_func
return RemotePLCObjectProxy._getattr_(attrName)(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/Pyro/core.py", line 381, in _call_
return self._send(self._name, args, kwargs)
File "/usr/lib/python2.7/dist-packages/Pyro/core.py", line 456, in _invokePYRO
return self.adapter.remoteInvocation(name, Pyro.constants.RIF_VarargsAndKeywords, vargs, kargs)
File "/usr/lib/python2.7/dist-packages/Pyro/protocol.py", line 457, in remoteInvocation
return self._remoteInvocation(method, flags, *args)
File "/usr/lib/python2.7/dist-packages/Pyro/protocol.py", line 532, in _remoteInvocation
answer.raiseEx()
File "/usr/lib/python2.7/dist-packages/Pyro/errors.py", line 72, in raiseEx
raise self.excObj
AttributeError: 'PLCObject' object has no attribute '_ResetLogCount'
+--- This exception occured remotely (Pyro) - Remote traceback:
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/Pyro/protocol.py", line 719, in _handleInvocation2
res = obj.Pyro_dyncall(req[1],flags,req[3]) # (method,flags,args)
File "/usr/lib/python2.7/dist-packages/Pyro/core.py", line 108, in Pyro_dyncall
return getattr(self.delegate or self,method) (args,*keywords)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/PLCObject.py", line 101, in ResetLogCount
if self._ResetLogCount is not None:
AttributeError: 'PLCObject' object has no attribute '_ResetLogCount'
+--- End of remote traceback

// import Nevow.Athena
// import Divmod.Base

function updateAttr(id, param, value) {
  Nevow.Athena.Widget.fromAthenaID(1).callRemote('HMIexec', 'setattr', id, param, value);
}

var svguiWidgets = new Array();

var currentObject = null;
function setCurrentObject(obj) {
	currentObject = obj;
}
function isCurrentObject(obj) {
	return currentObject == obj;
}

function getSVGElementById(id) {
	return document.getElementById(id);
}

function blockSVGElementDrag(element) {
	element.addEventListener("draggesture", function(event){event.stopPropagation()}, true);
}

LiveSVGPage.LiveSVGWidget = Nevow.Athena.Widget.subclass('LiveSVGPage.LiveSVGWidget');
LiveSVGPage.LiveSVGWidget.methods(

    function handleEvent(self, evt) {
        if (currentObject != null) {
            currentObject.handleEvent(evt);
        }
    },

    function receiveData(self, data){
        dataReceived = json_parse(data);
        gadget = svguiWidgets[dataReceived.id]
        if (gadget) {
        	gadget.updateValues(json_parse(dataReceived.kwargs));
        }
        //console.log("OBJET : " + dataReceived.back_id + " STATE : " + newState);
    },
    
    function init(self, arg1){
        //console.log("Object received : " + arg1);
        for (ind in arg1) {
            gad = json_parse(arg1[ind]);
            args = json_parse(gad.kwargs);
            gadget = new svguilib[gad.__class__](self, gad.id, args);
            svguiWidgets[gadget.id]=gadget;
            //console.log('GADGET :' + gadget);
        }
        var elements = document.getElementsByTagName("svg");
        for (var i = 0; i < elements.length; i++) {
        	elements[i].addEventListener("mouseup", self, false);
        }
        //console.log("SVGUIWIDGETS : " + svguiWidgets);
    }
);