Background images

It looks like as a result of use `background-size: cover;`  the background looks icky for certain aspect ratios of viewport. Observed on a 27" Cinema Display.

**Before:**

![screen shot 2013-09-18 at 21 33 34](https://f.cloud.github.com/assets/868834/1168584/7fe5a0ca-20a2-11e3-8421-08e61e85cb70.png)

**After:**

![screen shot 2013-09-18 at 21 33 46](https://f.cloud.github.com/assets/868834/1168588/8625d464-20a2-11e3-9e09-d55508af9f50.png)

**Notes:**

I've updated all 4 background images but I could only find 2 being used (`background-home.jpg` on the homepage and `background-gaming.jpg` on `/gaming/`). If the other images are no longer used maybe we can remove them or at least remove the unnecessary rules from the CSS. Either way I updated the images anyway just in case. 

I've tried to keep the image file sizes as close to the previous version as possible, but jpeg compression ontop of jpeg compression gets to look kind of bad. Do let me know if you have the original versions of these images at higher quality and I can easily remake them if they aren't 100% suitable.