Date and Time Preferences implementation

[trunkmaster]

Date and time, timezone, NTP settings management.

[zeroheure]

These preferences are allways set only once (or often set only once). I can be wrong, but these are mostly done during system installation. So there is really minor needs for this. For example, I don't even know where it is located in my desktop system preferences (KDE).
I think you can forget it for 1.0, don't try to be perfect. This is not a big deal to setup in CLI, assuming NextSpace will have only experienced users at first.

Actualy, this can be an easy task for new developpers.

[trunkmaster]

@zeroheure, I'm interested in this implementation from the authentication point of view - changing date time in default install requires root privilidges. Whlie many things in NextSpace is not implemented yet such easy task is not that easy than it seeems. ;)