Rename simple action runner to subprocess action runner, create an enum for config parsing.
More tests.
Include run scripts in the package.
Add docs about action runners.
Merge pull request #214 from dnephin/31_kill_running_actions

Kill a running action
Merge branch 'release_0.6.1' of github.com:Yelp/Tron into 155_max_runtime_for_jobs