Updated the README with new Carthage instructions. Also updated a bunch of old content.
Updated the README with new Carthage instructions. Also updated a bunch of old content.

relayrides/objective-c-sdk,relayrides/objective-c-sdk,optimizely/objective-c-sdk,optimizely/objective-c-sdk,relayrides/objective-c-sdk,optimizely/objective-c-sdk,optimizely/objective-c-sdk,relayrides/objective-c-sdk