Fix "currently" method

The current behavior is not consistent with comment above method isCurrentlyVisible():

I have removed constant QUICK_METHODS (I don't understand why this list contains "shouldNotBeVisible" and don't "shouldNotBeCurrentlyVisible") and QUICK_CLASSES, which cannot be changed by users.
For example if I extends WebElementFacadeImpl and overide isCurrentlyVisible method, I will be waiting for implicit timeout.
Also I cannot  find any cases when we execute method from PageObject.class.

Thus it would be better to make the behavior more clear. 
But it's also bad implementation because of we go throughout all stacktrace method! And it can cause problems with the chain of fluent method.