Try
This will relog you into iCloud and with a bit experimentation you'll get iMessage running, but App Store/Continuity won't work that easily.
https://forums.developer.apple.com/message/19143
Code:
rm ~/Library/Preferences/com.apple.SetupAssistant.plist && rm -rf ~/Library/Application\ Support/iCloud/Accounts && /System/Library/CoreServices/Setup\ Assistant.app/Contents/SharedSupport/SetupAssistantSpringboard
This will relog you into iCloud and with a bit experimentation you'll get iMessage running, but App Store/Continuity won't work that easily.
https://forums.developer.apple.com/message/19143