Added a stats class for bamstats

biopet-tools/src/main/scala/nl/lumc/sasc/biopet/tools/bamstats/Stats.scala

+package nl.lumc.sasc.biopet.tools.bamstats
+
+/**
+ * Created by pjvanthof on 05/07/16.
+ */
+case class Stats() {
+
+  var totalReads = 0L
+
+  def +(other: Stats): Stats = {
+    this.totalReads += other.totalReads
+    this
+  }
+}