Added general trait (BiopetQScript) that now have multisample functions

...rc/main/java/nl/lumc/sasc/biopet/core/BiopetQScript.scala

...ework/src/main/java/nl/lumc/sasc/biopet/core/Config.scala

...a/nl/lumc/sasc/biopet/pipelines/flexiprep/Flexiprep.scala

gatk/examples/test.json

...c/main/java/nl/lumc/sasc/biopet/pipelines/gatk/Gatk.scala

.../java/nl/lumc/sasc/biopet/pipelines/mapping/Mapping.scala