Helmet sprite tweaks

So I spent about an hour tweaking these to where I wanted them and thinking over the detail of how they'd mesh with sunglasses and stuff.

Old / New
![ss 2014-12-15 at 08 49 16](https://cloud.githubusercontent.com/assets/7247232/5448789/3b3566d6-849c-11e4-847f-f4ae84258c23.png) ![ss 2014-12-15 at 08 50 06](https://cloud.githubusercontent.com/assets/7247232/5448790/4101c1d6-849c-11e4-864e-3792e6a73056.png)

Notable changes:
Less blue tint to visor (security wears shades anyway, much easier to see said shades when the visor is less blue)
Wider visors, like our old helmet sprites for 'muh nostalgia' and revealing more of the officer's face
Shading improvements over old sprites
^ These same changes have been applied to the nanotrasen 'swat' helmet as well

You can call them "my" sprites now too :+1: