Improve the plugin manager gui.
There is only two categories : plugins and system.
Add a message to prevent the user if he wants to start, stop, refresh a plugin system
Add icon
Fix the jlist with empty selection. If a selection is empty the first index is selected.
Clean the code
Remove unused icon
Fix OSGi panel components
remove unused files
Merge pull request #738 from nicolas-f/ebocher-pluginManager

Plugin manager fix #735


New menu and categories to improve the user experience.
Only two categories : plugins and systems.

Add a popup message to prevent OrbisGIS unstable if a user stop or start a system plugin.