Validation element handler

Since calls to WebDriver are async, even simple interaction with elements can be a headache. With FubuValidation elements are validated after data is input, either after losing focus, or a timeout has been reached when entering data that triggers validation. The problem is that some follow on actions may be dependent on that validation being complete before proceeding. This new element handler will use a new Validation Count strategy applied on the client that tracks how many times validation has occurred. The ValidationElementHandler simply takes note of the current count, defers to other element handlers, then waits for that count to increase before proceeding. Testing with WebDriver just got more stable.