Swift 3.2/4

All issues associated with this milestone can be found using this filter.

Added

• Swift 3.2 support
• Swift 4 support

Additional

• Defaults to Swift 3.2 while we await a Swift 4 release from Mixpanel.
• If you'd like to support the Swift 4 version of Simcoe regardless, set your project's SWIFT_VERSION to 4 and append the following code snippet at the end of your Podfile to specify the 3.2 version of Mixpanel.

post_install do |installer|
    installer.pods_project.targets.each do |target|
        if target.name == 'Mixpanel-swift'
            target.build_configurations.each do |config|
                config.build_settings['SWIFT_VERSION'] = '3.2'
            end
        end
    end
end