Add functions to populate with env variables.
Merge branch 'master' of github.com:Nextdoor/kingpin into populate_with_env
Parse JSON for environment variables
Add build status to README
remove bogus test
Detect non-converted environment variables in JSON.

Also cleans up the Exceptions to all subclass from a common one.
Remove camelCase
Remove unused getRootPath() method
Move logger setup entirely into kingpin.utils.

Also remove some annoying DEBUG log statements from the str_to_class
method.
Make 'get_actor()' a utility method that can be reused by multiple classes.

This allows the actors.group.BaseGroup actor to use the same method as
the CLI tool (deploy.py) for creating the initial actor object.
Cleaner exception catching
Add more clear logging when the actor fails to init.
Clean up JSON error handling
Create a new Threadpool for every thread_coroutine() call.

The threadpool objects are supposed to have .shutdown() called when
they're done being used. During the Tornado unit tests we seem to run
into IOErrors on the threadpool objects. This patch creates a new fresh
threadpool object and uses it in a 'with' context, which should force it
to be shut down properly before the method ever returns.
line length
Add simple convert_json_to_dict() test
Merge branch 'master' into populate_with_env
Remove demjson requirement
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()