Add tasks for all the new languages

Task/Sorting-algorithms-Merge-sort/Swift/sorting-algorithms-merge-sort.swift

@@ -0,0 +1,45 @@
+func mergeSort<T:Comparable>(inout list:[T]) {
+    if list.count <= 1 {
+        return
+    }
+
+    func merge(var left:[T], var right:[T]) -> [T] {
+        var result = [T]()
+
+        while left.count != 0 && right.count != 0 {
+            if left[0] <= right[0] {
+                result.append(left.removeAtIndex(0))
+            } else {
+                result.append(right.removeAtIndex(0))
+            }
+        }
+
+        while left.count != 0 {
+            result.append(left.removeAtIndex(0))
+        }
+
+        while right.count != 0 {
+            result.append(right.removeAtIndex(0))
+        }
+
+        return result
+    }
+
+    var left = [T]()
+    var right = [T]()
+
+    let mid = list.count / 2
+
+    for i in 0..<mid {
+        left.append(list[i])
+    }
+
+    for i in mid..<list.count {
+        right.append(list[i])
+    }
+
+    mergeSort(&left)
+    mergeSort(&right)
+
+    list = merge(left, right)
+}