Add a better pattern for each problem

[ignacio-chiazzo]

Create a better pattern for problems:

• Make sure each object implements its main function and export it.
• Don't stop the main if any of the classes didn't implement the function
• Put a warning with red letters whenever a problem wasn't added a main function
• Fail test if a class doesn't implement main function an export it?

Create a structure for every problem like this? :

/* 
@param {string} a
@param {number} b
*/

var problemName = function(a,b...) {...}

var testCases = function() {
    console.log(problemName(...));
}

var main = function() {
   // print  something useful if needed
   testCases();
}

module.exports.main = main;