Added update monitor that will set the system LED if updates are available.

Hi Merelin,

I've added an update monitor to mediasmartserverd. If you like it please merge it.

Functionality:
It sets the system LED according to the update status:
Updates available -> Blue.
Security updates available -> Purpel
Reboot required -> Red

The functionality was tested in ubuntu server 12.10 64bit and requires update-notifier-common.

Best regards,
Kai