Transform Morse code data model to text

TextTransformation.swift

func createMorseCodeText(from encodedMessage: EncodedMessage) -> String {
    let transformation = MorseTransformation(
        dot:             ".",
        dash:            "-",
        markSeparator:   "",
        symbolSeparator: " ",
        termSeparator:   "\n")
    let characters = transformation.apply(to: encodedMessage)
    return characters.joinWithSeparator("")
}