More precise downcast for .getProp

@smuir pointed out that the downcast inside the Option doesn't do any
checking (beyond checking the Option, of course). It doesn't much
matter here, since it's an Any (which we can't do any checking on,
anyway), but if that ever changed, this could be a weird hole for
bugs to hide in.

Author: clinedome-work

src/main/scala/com/comcast/xfinity/sirius/api/SiriusConfiguration.scala

@@ -319,7 +319,9 @@ class SiriusConfiguration {
    *
    * @return Some(value) if it exists, or None if not
    */
-  def getProp[T](name: String): Option[T] = conf.get(name).asInstanceOf[Option[T]]
+  def getProp[T](name: String): Option[T] = conf.get(name).map {
+    case value => value.asInstanceOf[T]
+  }
 
   /**
    * Get a property with a default fallback