function for undiscover processing unit
processingunitwatcher handles forgetting processing units for master
updated tests
fiddling with tests
added tests to IlluminaProcessingUnitWatcherExecutorActorTest
clarifying comments, some refactoring to allow more logic method calls
pass string instead of unit to ProcessingUnitWatcherActor and refactoring/test modifications to accommodate that
Merge pull request #41 from b97pla/feature/restart_finished_demultiplexing

Feature/restart finished demultiplexing