Glances API RESTful implementation.

        Return the process stats (dict) for the given item=value
        HTTP/200 if OK
        HTTP/400 if plugin is not found
        HTTP/404 if others error

def _api_value(self, plugin, item, value):
        """Glances API RESTful implementation.

        Return the process stats (dict) for the given item=value
        HTTP/200 if OK
        HTTP/400 if plugin is not found
        HTTP/404 if others error
        """
        return self._api_itemvalue(plugin, item, value)