Add tasks for all the new languages

Task/Tokenize-a-string/Swift/tokenize-a-string-1.swift

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+let text = "Hello,How,Are,You,Today"
+let tokens = text.characters.split(",").map{String($0)} // for single-character separator
+print(tokens)
+let result = tokens.joinWithSeparator(".")
+print(result)

Task/Tokenize-a-string/Swift/tokenize-a-string-2.swift

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+let text = "Hello,How,Are,You,Today"
+let tokens = split(text, { $0 == "," }) // for single-character separator
+println(tokens)
+let result = ".".join(tokens)
+println(result)

Task/Tokenize-a-string/Swift/tokenize-a-string-3.swift

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+import Foundation
+
+let text = "Hello,How,Are,You,Today"
+let tokens = text.componentsSeparatedByString(",")
+print(tokens)