Added framework project for Carthage support

[eliburke]

@iscriptology here's a preliminary PR for Carthage support.

I think that it is possible to create a project that supports both CocoaPods and Carthage, but I don't know how, so for now I've done it as a separate xcodeproj

You will need to tag a new release for it to actually become available to Carthage (0.2.1 or 0.3.0)

[yosef-abraham]

I need to find time to investigate Carthage before I merge this. (as I never used it)
Hopefully I'll do it soon.
Thank you for the PR, waiting for your MP one :)

[eliburke]

So... two things about the MsgPack merge...

1. it's dependent on the carthage PR. If you want me to PR just the source file I can, and you can figure out the cocoa pods update
2. it's dependent on my fork of a2/messagepack.swift-- I'm waiting for him to integrate a carthage patch.

FYI, carthage is pretty simple. It just needs a xcodeproj that builds a framework and has a build scheme that is marked as shared. Swamp is just a little more complex than many because of the nested frameworks.

[sberryman]

Is there any reason carthage support hasn't been merged in yet?

[tomtom5152]

Would also like to see this merged as I'd rather not have two dependancy managers.