Update WebDriverContainer.php

added function welement() [wait and get element pointer], it' an improvement over element() function. Since elemet() fails to find an element in huge% of cases due a speed with which an element appears on a dynamic page. This function is a helper and might be not a high-blood codding style, but I myself follow middle-path. This helper though reduced my test cases twice in size. If you have any suggestion of how to put it the right way - you are welcome