EarlGrey 2.0 | Publish as framework

> Because static libraries add additional problems that must be solved: like how to expose the headers for the projects that use the dependency. Static frameworks support this nicely (it's basically a static library that's bundled with the headers), so there's no reason to support static libraries by themselves.
>
> https://github.com/Carthage/Carthage/issues/2685#issuecomment-455258498

Based on feedback from the Carthage team, I recommend that EarlGrey 2 move the static libs to static frameworks. Otherwise it's not possible for EarlGrey 2 to be properly consumed by Carthage.