Reorganized project, added Travis-CI.

I looked around for a color hex library and this is the best I could find. 

Reorganized project around CocoaPods. Some of this is described [in this blog post](http://code.dblock.org/reorganizing-cocoapod-folder-structure-for-unit-and-integration-testing). Basically the .podspec is now committed to the top level and when someone checks out the project they just do `pod install` and open a newly generated EDColor.xcworkspace with everything ready to go.

Added Travis-CI which builds everything and runs tests. You have to enable this on your project before you merge this on travis-ci.org. You can see it [succeed on mine here](https://travis-ci.org/dblock/color/builds/22977879).