fixes temporary file handling and unit tests
* temporary files of bytestreammanager are now deleted on exit: fixes #116
* moved DB tests in plato-model to integration test phase
  Remember to run integration tests with mvn clean install, instead of mvn clean package,
  as in multi module projects referenced projects are loaded from the (local)maven repository.
  (this does make sense, as you could refer to an older version, while continue to work on the sub projects)
  fixes #86