raava.worker: Removed task.fork() (may be implemented in userspace), added save exceptions
Refactoring: job_path instead of difficult zoo.join()
Added comment about double pickling in splitter
splitter: Log about the split in the cycle
raava.worker: Added comment about traceback.exc_info()
raava.worker._Task: simplfied state/handler assert
raava.splitter: Fixed comment about double-pickling
raava.zoo: Comment about CONTROL_TASK_EXC
Merge pull request #40 from mdevaev/exc-trace-2

Removed task.fork(), added save exceptions