Add tasks for all the new languages

Task/Loops-Downward-for/Swift/loops-downward-for-1.swift

@@ -0,0 +1,3 @@
+for i in stride(from: 10, through: 0, by: -1) {
+  println(i)
+}

Task/Loops-Downward-for/Swift/loops-downward-for-2.swift

@@ -0,0 +1,3 @@
+for i in lazy(0...10).reverse() {
+  println(i)
+}

Task/Loops-Downward-for/Swift/loops-downward-for-3.swift

@@ -0,0 +1,3 @@
+for i in reverse(0 ... 10) {
+  println(i)
+}

Task/Loops-Downward-for/Swift/loops-downward-for-4.swift

@@ -0,0 +1,3 @@
+for var i = 10; i >= 0; i-- {
+  println(i)
+}

Task/Loops-Downward-for/Swift/loops-downward-for-5.swift

@@ -0,0 +1,3 @@
+for i in (0...10).reversed() {
+    print(i)
+}