Add tasks for all the new languages

Task/Classes/Coco/classes.coco

@@ -0,0 +1,15 @@
+class Rectangle
+  # The constructor is defined as a bare function. This
+  # constructor accepts one argument and automatically assigns it
+  # to an instance variable.
+  (@width) ->
+
+  # Another instance variable.
+  length: 10
+
+  # A method.
+  area: ->
+    @width * @length
+
+# Instantiate the class using the 'new' operator.
+rect = new Rectangle 2