Separate options event name and actions event name

It will mix up the event when:

```
program
  .version('0.0.1')
  .option('--foo', 'bar')
  .option('--verbose', 'do stuff');

program.parse(['node', 'test', '--foo', 'verbose']);
program.foo.should.be.true;
should.not.exist(program.verbose);
```

Add prefix to each event name to avoid