twitter/commons — pull request #327 by simonrad (2014-09-26 22:35:22+00:00)
Title: Add to Application class a method to set the usage message automatically.

The usage message will show the available commands and their docstrings.

Example auto-generated usage message:

```
Usage: Please run with one of the following commands:
cron_once Execute the cron once.
The cron fetches from git, does validation, and updates ZooKeeper.
debugger Launch into the debugger, giving you a Python REPL with access to Git and ZooKeeper.
cron_continuously Execute the cron every CRON_INTERVAL_SECONDS seconds.
If there's an exception, the process will fail. Otherwise, the process will run forever.
The cron fetches from git, does validation, and updates ZooKeeper.
server Run as the server.
The server is mainly used for monitoring and diagnostics.
Takes one argument: The port on which to accept requests.

Options:
-h, --help, --short-help
show this help message and exit.
--long-help show options from all registered modules, not just the
__main__ module.
```