Merge pull request #145 from anyman/master

Changing HadoopJobRunner to use move_dir
Merge pull request #146 from anyman/master

Revert "Changing HadoopJobRunner to use move_dir
Retry if ping of scheduler fails

* Makes ping interval configurable
* Also adds accessible stop() method to stop workers' keep-alive-threads
Additional test for new Worker.stop method
Merge pull request #147 from spotify/freider/ping_retry

Retry if scheduler ping fails
Refactor Worker.add

Refactored the Worker.add method to make it more readable. Breaks out
some of the email/error logic for across the module.
Flatten recursive add into an explicit list-based stack
Remove __del__ on worker as it's undeterministic
Merge pull request #148 from spotify/freider/worker_add_refactor

Refactor Worker.add
Improve parameter parsing so it doesn't break the scheduler on weird parameter values

Adds failing unit test exposing broken parameter split
Merge pull request #149 from spotify/freider/broken_param_split

Improve scheduler-side parameter parsing
Removing upstream_status from serialization info