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"
Also, again, not important, but FYI, there's a slightly shorter way to do this if you don't care about that log statement.

```scala

Try {
  assertExistsAndDisplayed(findByTestAttribute(GalleryPictureId, galleryElement))
}.toOption.isDefined

```