Fixed bug in loading the mainClass for biopet tools

...c/sasc/biopet/pipelines/bammetrics/BammetricsReport.scala

.../scala/nl/lumc/sasc/biopet/core/ToolCommandFunction.scala

...scala/nl/lumc/sasc/biopet/core/report/ReportBuilder.scala

...test/scala/nl/lumc/sasc/biopet/core/ToolCommandTest.scala

...scala/nl/lumc/sasc/biopet/pipelines/carp/CarpReport.scala

...umc/sasc/biopet/pipelines/flexiprep/FlexiprepReport.scala

...ala/nl/lumc/sasc/biopet/pipelines/gears/GearsReport.scala

...nl/lumc/sasc/biopet/pipelines/gentrap/GentrapReport.scala

...nl/lumc/sasc/biopet/pipelines/mapping/MappingReport.scala

...ala/nl/lumc/sasc/biopet/pipelines/shiva/ShivaReport.scala