Add an example to create/delete/list Google Cloud Storage buckets.

How about combining the arg parsing with the comment selection? Something like:
```
// parse args required for all commands and command
ManageBuckets manageBuckets = ...
if (command.equals(...)) {
  // parse additional args for this command
  manageBuckets...
} else if (command.equals(...)) {
  // parse options for this command
  ...
}
```