Bumped to version v2.0.0.

Some of the changes in master are not backward compatible with the v1.0 tag, according to the rules of semantic versioning (http://semver.org) which is used for CocoaPods, hence the bump to v2.0.0.

After merging this pull request, would you minding tagging master as "v2.0.0"? The exact name is important as it is referred to in the .podspec file.

Once tagged, I'm happy to submit the updated .podspec to CocoaPods so people can start pulling down the new version.

Thanks!