Added extra check for forcing abolute paths for input files

public/biopet-core/src/main/scala/nl/lumc/sasc/biopet/core/BiopetQScript.scala

@@ -99,7 +99,8 @@ trait BiopetQScript extends Configurable with GatkLogging { qscript: QScript =>
 
     inputFiles.foreach { i =>
       if (!i.file.exists()) Logging.addError(s"Input file does not exist: ${i.file}")
-      else if (!i.file.canRead) Logging.addError(s"Input file can not be read: ${i.file}")
+      if (!i.file.canRead) Logging.addError(s"Input file can not be read: ${i.file}")
+      if (!i.file.isAbsolute) Logging.addError(s"Input file should be an absulute path: ${i.file}")
     }
 
     functions.filter(_.jobOutputFile == null).foreach(f => {