Initial attempt at adding Carthage support

[ArtSabintsev]

No description provided.

[ArtSabintsev]

@mikemee Added Carthage support and tested it. Seems to work.

• Add the following to your cart file to access this branch:

// This pulls the repo from Siren's carthage branch, which is the only way to add carthage support without pulling into the main branch.

github "ArtSabintsev/Siren" "carthage"

• Then, run

carthage update

• Finally, do the following:

On your application targets’ “General” settings tab, in the “Linked Frameworks and Libraries” section, drag and drop each framework you want to use from the Carthage/Build folder on disk.

[ArtSabintsev]

Accepted the PR since it seems to work.