Added Notification Area Icon and minimize to Notification Area

As requested per issue #43 added systray (Notification Area) support. There's an option that causes the OBS window to disappear besides adding the icon.
The icon gets a red dot when OBS is active.

The options:
![General Settings](https://f.cloud.github.com/assets/2565912/279178/1b267662-9111-11e2-9336-d6057bc31742.png)

The tray:
![Notification Area while idle](https://f.cloud.github.com/assets/2565912/279179/1ff6ed98-9111-11e2-9675-8616fac7b316.png)

When recording or previewing:
![Notification Area while recording](https://f.cloud.github.com/assets/2565912/279180/23fcdde4-9111-11e2-806b-e1ccb0492c06.png)

Minimized and not recording, with "Minimize to Notification Area" checked:
![tray3](https://f.cloud.github.com/assets/2565912/279194/ed28f9b4-9111-11e2-8220-71843131a3e2.png)