Scala test fw

First attempt to use the inhouse Scala testing framework with one test for checking the picture overlay functionality. Keep in mind that I am a beginner Scala dev so code will likely look very "Javaish"
Yeah, `flatMap`:

```scala
val errors = elementsToCheck flatMap { element => 
  try {
    if (!webElement.isDisplayed) {
      Some(s"Web element was not displayed: $webElement")
    } else {
      None
    }
  } catch {
    case e: WebDriverException => 
      logger.warn(s"Web element was not displayed: $webElement", e)
      Some(e.getMessage)
  }
}
```