Add support for Cinnamon Menu Applet and PanelLauncher.

This commit allow:
- Drag and drop from Cinnamon PanelLauncher... 
- Register this Applet as a PanelLauncher.
- Recive object from Cinnamon Menu Applet in the function acceptNewLauncher...

This commit remove:
- Old way to support Configurable Menu.

Observation:
- There are not problem with Drag and Drop Desklets, the problem it's that the Desket are not set in the same position where you droped it, so will be complete behind the panel...
- Will be good have support for modify the launchers or add new launchers... See the Panel launcher Cinnamon Applet, and also https://github.com/linuxmint/Cinnamon/blob/24c2d7526edfc3b7b02deb3414b85d3b542f8182/files/usr/lib/cinnamon-desktop-editor/cinnamon-desktop-editor.py
- Could be good have a common (general functions in Cinnamon) way to remove application and also know if some application id is in the launcher.