bump tornado for https://github.com/tornadoweb/tornado/commit/8e7effdaefaddc5b61ba0aa6ff8e94f1422b6092
Misc fixes all aimed at better exception handling.

1. Leverage utils.retry() inside utils.thread_coroutine().
2. Replace thread_coroutine() with tornado.concurrent.run_on_executor()
3. Add simple exception logger for threads.
4. bump tornado for https://github.com/tornadoweb/tornado/commit/8e7effdaefaddc5b61ba0aa6ff8e94f1422b6092
5. use python-rightscale retries branch
6. Retry on all exceptions rather than selected ones.
7. Allow the execute job to take longer (unit test)
Add docstrings to utils.exception_logger()
Convert aws.elb package to use tornado.concurrent.run_on_executor().
Convert aws.sqs package to use tornado.concurrent.run_on_executor()
Remove utils.thread_coroutine in favor of tornado.concurrent.run_on_executor()
Fix example code
Clean up documentation after switching to tornado.concurrent.run_on_executor()
Merge branch 'master' into bad_status_line
Wrap all @run_on_executor methods in @exception_logger.

This will provide better Exception logging when a thread raises an
exception.
Typo in regex
Revert "Typo in regex"

This reverts commit 7b13f96584054c5fcaefef96a715f12b466fe3b1.
Typo in regex
Merge pull request #37 from Nextdoor/bad_status_line

Increase reliability around connection failures
Merge branch 'master' of github.com:Nextdoor/kingpin into populate_with_env