- add SmartHome.get_plugin_name() and Plugins.get_plugin_name() to retrieve the plugin name
  for given plugin instance
# can also be used instead of plugin ident (which is the thread`s identifier) for
# better readability
- use get_plugin_name() instead of get_plugin_ident() to register scheduler with
  the plugin name instead of plugin ident, which can not be used to identify the
  plugin instance