Update Map.swift for Swift 3
Update Map.swift for Swift 3

In preparation for Swift 3 -- `++` is deprecated: it will be removed in Swift 3 (https://github.com/apple/swift-evolution/blob/master/proposals/0004-remove-pre-post-inc-decrement.md)
Hearst-DD/ObjectMapper,cfraz89/ObjectMapper,Busta117/ObjectMapper,Busta117/ObjectMapper,Hearst-DD/ObjectMapper,cfraz89/ObjectMapper