Change version command

public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/varscan/Varscan.scala

@@ -23,7 +23,7 @@ abstract class Varscan extends BiopetJavaCommandLineFunction with Version {
 
   jarFile = config("varscan_jar")
 
-  def versionCommand = super.commandLine
+  def versionCommand = s"$executable -jar $jarFile"
   def versionRegex = """VarScan v(.*)""".r
 }