SearchContext for ExpectedConditions (if it's possible)

Commit summary :
Created a specific class for ```ExpectedConditions``` that are possible to run with just ```SearchContext``` and don't require ```WebDriver```.

What's this good for?
Many of the ```ExpextedConditions``` that are now bound to use ```WebDriver```don't actually require ```Webdriver``` and they're happy with ```SearchContext```. So let's widen their usage!