Add CollectRnaSeqMetrics histogram to summary file

public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/extensions/picard/CollectRnaSeqMetrics.scala

@@ -85,7 +85,9 @@ class CollectRnaSeqMetrics(val root: Configurable) extends Picard with Summariza
       "output_chart" -> chartOutput
     ).collect { case (key, Some(value)) => key -> value }
 
-  def summaryStats = Picard.getMetrics(output).getOrElse(Map())
+  def summaryStats = Map(
+    "metrics" -> Picard.getMetrics(output).getOrElse(Map()),
+    "histogram" -> Picard.getHistogram(output).getOrElse(Map()))
 
   override def commandLine = super.commandLine +
     required("INPUT=", input, spaceSeparated = false) +