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"
As this is used in two places, move it out into a `val` above?

```scala

val testDependencies = Seq(
  "org.seleniumhq.selenium" % "selenium-java" % "2.42.0",
  "com.google.code.findbugs" % "jsr305" % "1.3.+"
)

val integrationTestLib = application("intergration-test-lib"), Some("integration-tests/integration-test-lib")).settings(
  libraryDependencies ++= testDependencies
)

// ... etc.

```