add 'expect' and 'should' modules

test/test.js

 var assert = require('chai').assert;
+var expect = require('chai').expect;
+var should = require('chai').should() //actually call the function
 
-it('doesn\'t do anything', function(){
+var foo = 'bar';
 
+it('doesn\'t do anything', function(){
+  assert.typeOf(foo, 'string', 'foo is a string');
 });