Some README.md examples don't work

[edmulraney]

Might be worth updating the README to include installing the 'should' library otherwise some examples will fail.

Some examples try to call should.equal on the result object of support.isElementPresent(...).

Example:

this.Then(/^I should not see a "([^"]*)" link$/, function(link, callback) {
    support.isElementPresent(this, link, function(result){
      result.should.equal(false);
      setTimeout(callback, 1000);
    });
  });

Alternatively you could remove the should stuff and just use:

 this.Then(/^I should not see a "([^"]*)" link$/, function(link, callback) {
    support.isElementPresent(this, link, function(result){
      if(result) {
        setTimeout(callback, 1000);
      } else {
        callback(new Error('Element not present'));
      }
    });
  });