Add tasks for all the new languages

Task/Run-length-encoding/Swift/run-length-encoding-1.swift

@@ -0,0 +1,14 @@
+import Foundation
+
+// "WWWBWW" -> [(3, W), (1, B), (2, W)]
+func encode(input: String) -> [(Int, Character)] {
+    return input.characters.reduce([(Int, Character)]()) {
+        if $0.last?.1 == $1 { var r = $0; r[r.count - 1].0++; return r }
+        return $0 + [(1, $1)]
+    }
+}
+
+// [(3, W), (1, B), (2, W)] -> "WWWBWW"
+func decode(encoded: [(Int, Character)]) -> String {
+    return encoded.reduce("") { $0 + String(count: $1.0, repeatedValue: $1.1) }
+}