Adding `@timeout` annotation
Adding `WaitingElementLocator`
Adding `waitFor` method to ISearchContext interface

1. implementing `waitFor` method in `ElementContainer` (HtmlElements)
2. adding test in HtmlElementsLive too
Adding dummy Block::waitFor method for BEM module
Use `WaitingElementLocator` by default, since it preserves BC
Merge pull request #25 from aik099/waiting-element-locator

Implement "WaitingElementLocator"
Cache found elements inside the locator