Fix for issue 3550 (Consider making the control panel able to manage remote servers)

The limitations of the control panel when managing a remote server compared to managing the local instance are:

- It cannot start/stop/restart the server
- It cannot manage the server and update the server when it is off-line.
- It cannot update the java settings.
- It cannot update/view the windows service settings.
- It cannot verify indexes.

The main changes at the user interaction level are that the first dialog that is displayed proposes the user to manage the local instance or the remote instance.  Moreover the user can choose to change the managed instance by selecting a new menu Item ('File'/'Server to Administer...').