Fix memory requirements

public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/tools/PrefixFastq.scala

@@ -31,6 +31,9 @@ import scala.collection.JavaConversions._
 class PrefixFastq(val root: Configurable) extends BiopetJavaCommandLineFunction {
   javaMainClass = getClass.getName
 
+  memoryLimit = Some(1.0)
+  override val defaultVmem = "4G"
+
   @Input(doc = "Input fastq", shortName = "I", required = true)
   var inputFastq: File = _