Add more colors to CPColor

[nabs749]

Hi all

I've been looking into issue 182: http://github.com/280north/cappuccino/issues#issue/182

Here is my commit: http://github.com/nabs749/cappuccino/commit/229b9465847f80ed2bb75ca451e5a2d5ba8bd154

There's not really much to say about it - the CPColor class was
missing some of the named colors (specifically brownColor, cyanColor,
magentaColor, orangeColor and purpleColor) and I added them based on
the information I found here:
http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/Classes/NSColor_Class/Reference/Reference.html#//apple_ref/occ/clm/NSColor/cyanColor

Let me know if you have any feedback.

Regards
Nabil